diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
index 6f69f8f46165..e5898efe7f6b 100644
--- a/lib/matplotlib/__init__.py
+++ b/lib/matplotlib/__init__.py
@@ -119,7 +119,10 @@
 import functools
 # cbook must import matplotlib only within function
 # definitions, so it is safe to import from it here.
-from matplotlib.cbook import is_string_like, mplDeprecation, dedent, get_label
+from matplotlib.cbook import (is_string_like,
+                              mplDeprecation,
+                              dedent, get_label,
+                              sanitize_sequence)
 from matplotlib.compat import subprocess
 from matplotlib.rcsetup import (defaultParams,
                                 validate_backend,
@@ -1541,7 +1544,7 @@ def _jupyter_nbextension_paths():
     'matplotlib.tests.test_units',
     'matplotlib.tests.test_widgets',
     'matplotlib.tests.test_cycles',
-    'matplotlib.tests.test_labeled_data_unpacking',
+    'matplotlib.tests.test_preprocess_data',
     'matplotlib.sphinxext.tests.test_tinypages',
     'mpl_toolkits.tests.test_mplot3d',
     'mpl_toolkits.tests.test_axes_grid1',
@@ -1649,12 +1652,15 @@ def test(verbosity=1, coverage=False):
 
 
 def _replacer(data, key):
+    """Either returns data[key] or passes data back. Also
+    converts input data to a sequence as needed.
+    """
     # if key isn't a string don't bother
     if not isinstance(key, six.string_types):
-        return key
+        return (key)
     # try to use __getitem__
     try:
-        return data[key]
+        return sanitize_sequence(data[key])
     # key does not exist, silently fall back to key
     except KeyError:
         return key
@@ -1673,7 +1679,7 @@ def _replacer(data, key):
 """
 
 
-def unpack_labeled_data(replace_names=None, replace_all_args=False,
+def _preprocess_data(replace_names=None, replace_all_args=False,
                         label_namer=None, positional_parameter_names=None):
     """
     A decorator to add a 'data' kwarg to any a function.  The signature
@@ -1707,6 +1713,8 @@ def foo(ax, *args, **kwargs)
         NOTE: callables should only be used when the names and order of *args
         can only be determined at runtime. Please use list of names
         when the order and names of *args is clear before runtime!
+
+    .. note:: decorator also converts MappingView input data to list.
     """
     if replace_names is not None:
         replace_names = set(replace_names)
@@ -1847,7 +1855,10 @@ def inner(ax, *args, **kwargs):
             label = None
 
             data = kwargs.pop('data', None)
-            if data is not None:
+
+            if data is None:  # data validation
+                args = tuple(sanitize_sequence(a) for a in args)
+            else:
                 if arg_names_at_runtime:
                     # update the information about replace names and
                     # label position
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 405e7c45b854..16d4e89978bd 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -12,7 +12,7 @@
 from numpy import ma
 
 import matplotlib
-from matplotlib import unpack_labeled_data
+from matplotlib import _preprocess_data
 
 import matplotlib.cbook as cbook
 from matplotlib.cbook import (mplDeprecation, STEP_LOOKUP_MAP,
@@ -906,7 +906,7 @@ def axvspan(self, xmin, xmax, ymin=0, ymax=1, **kwargs):
         self.autoscale_view(scaley=False)
         return p
 
-    @unpack_labeled_data(replace_names=['y', 'xmin', 'xmax'], label_namer="y")
+    @_preprocess_data(replace_names=['y', 'xmin', 'xmax'], label_namer="y")
     @docstring.dedent
     def hlines(self, y, xmin, xmax, colors='k', linestyles='solid',
                label='', **kwargs):
@@ -985,7 +985,7 @@ def hlines(self, y, xmin, xmax, colors='k', linestyles='solid',
 
         return coll
 
-    @unpack_labeled_data(replace_names=["x", "ymin", "ymax", "colors"],
+    @_preprocess_data(replace_names=["x", "ymin", "ymax", "colors"],
                          label_namer="x")
     @docstring.dedent_interpd
     def vlines(self, x, ymin, ymax, colors='k', linestyles='solid',
@@ -1067,7 +1067,7 @@ def vlines(self, x, ymin, ymax, colors='k', linestyles='solid',
 
         return coll
 
-    @unpack_labeled_data(replace_names=["positions", "lineoffsets",
+    @_preprocess_data(replace_names=["positions", "lineoffsets",
                                         "linelengths", "linewidths",
                                         "colors", "linestyles"],
                          label_namer=None)
@@ -1254,7 +1254,7 @@ def eventplot(self, positions, orientation='horizontal', lineoffsets=1,
 
     # ### Basic plotting
     # The label_naming happens in `matplotlib.axes._base._plot_args`
-    @unpack_labeled_data(replace_names=["x", "y"],
+    @_preprocess_data(replace_names=["x", "y"],
                          positional_parameter_names=_plot_args_replacer,
                          label_namer=None)
     @docstring.dedent_interpd
@@ -1403,7 +1403,7 @@ def plot(self, *args, **kwargs):
         self.autoscale_view(scalex=scalex, scaley=scaley)
         return lines
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+    @_preprocess_data(replace_names=["x", "y"], label_namer="y")
     @docstring.dedent_interpd
     def plot_date(self, x, y, fmt='o', tz=None, xdate=True, ydate=False,
                   **kwargs):
@@ -1477,7 +1477,7 @@ def plot_date(self, x, y, fmt='o', tz=None, xdate=True, ydate=False,
 
         return ret
 
-    # @unpack_labeled_data() # let 'plot' do the unpacking..
+    # @_preprocess_data() # let 'plot' do the unpacking..
     @docstring.dedent_interpd
     def loglog(self, *args, **kwargs):
         """
@@ -1539,7 +1539,7 @@ def loglog(self, *args, **kwargs):
 
         return l
 
-    # @unpack_labeled_data() # let 'plot' do the unpacking..
+    # @_preprocess_data() # let 'plot' do the unpacking..
     @docstring.dedent_interpd
     def semilogx(self, *args, **kwargs):
         """
@@ -1592,7 +1592,7 @@ def semilogx(self, *args, **kwargs):
         self._hold = b  # restore the hold
         return l
 
-    # @unpack_labeled_data() # let 'plot' do the unpacking..
+    # @_preprocess_data() # let 'plot' do the unpacking..
     @docstring.dedent_interpd
     def semilogy(self, *args, **kwargs):
         """
@@ -1645,7 +1645,7 @@ def semilogy(self, *args, **kwargs):
 
         return l
 
-    @unpack_labeled_data(replace_names=["x"], label_namer="x")
+    @_preprocess_data(replace_names=["x"], label_namer="x")
     @docstring.dedent_interpd
     def acorr(self, x, **kwargs):
         """
@@ -1707,7 +1707,7 @@ def acorr(self, x, **kwargs):
         """
         return self.xcorr(x, x, **kwargs)
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+    @_preprocess_data(replace_names=["x", "y"], label_namer="y")
     @docstring.dedent_interpd
     def xcorr(self, x, y, normed=True, detrend=mlab.detrend_none,
               usevlines=True, maxlags=10, **kwargs):
@@ -1797,7 +1797,7 @@ def xcorr(self, x, y, normed=True, detrend=mlab.detrend_none,
 
     #### Specialized plotting
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+    @_preprocess_data(replace_names=["x", "y"], label_namer="y")
     def step(self, x, y, *args, **kwargs):
         """
         Make a step plot.
@@ -1835,7 +1835,7 @@ def step(self, x, y, *args, **kwargs):
 
         return self.plot(x, y, *args, **kwargs)
 
-    @unpack_labeled_data(replace_names=["left", "height", "width", "bottom",
+    @_preprocess_data(replace_names=["left", "height", "width", "bottom",
                                         "color", "edgecolor", "linewidth",
                                         "tick_label", "xerr", "yerr",
                                         "ecolor"],
@@ -2270,7 +2270,7 @@ def barh(self, bottom, width, height=0.8, left=None, **kwargs):
                            bottom=bottom, orientation='horizontal', **kwargs)
         return patches
 
-    @unpack_labeled_data(label_namer=None)
+    @_preprocess_data(label_namer=None)
     @docstring.dedent_interpd
     def broken_barh(self, xranges, yrange, **kwargs):
         """
@@ -2331,7 +2331,7 @@ def broken_barh(self, xranges, yrange, **kwargs):
 
         return col
 
-    @unpack_labeled_data(replace_all_args=True, label_namer=None)
+    @_preprocess_data(replace_all_args=True, label_namer=None)
     def stem(self, *args, **kwargs):
         """
         Create a stem plot.
@@ -2456,7 +2456,7 @@ def stem(self, *args, **kwargs):
 
         return stem_container
 
-    @unpack_labeled_data(replace_names=['x', 'explode', 'labels', 'colors'],
+    @_preprocess_data(replace_names=['x', 'explode', 'labels', 'colors'],
                          label_namer=None)
     def pie(self, x, explode=None, labels=None, colors=None,
             autopct=None, pctdistance=0.6, shadow=False, labeldistance=1.1,
@@ -2683,7 +2683,7 @@ def get_next_color():
         else:
             return slices, texts, autotexts
 
-    @unpack_labeled_data(replace_names=["x", "y", "xerr", "yerr"],
+    @_preprocess_data(replace_names=["x", "y", "xerr", "yerr"],
                          label_namer="y")
     @docstring.dedent_interpd
     def errorbar(self, x, y, yerr=None, xerr=None,
@@ -3077,7 +3077,7 @@ def extract_err(err, data):
 
         return errorbar_container  # (l0, caplines, barcols)
 
-    @unpack_labeled_data(label_namer=None)
+    @_preprocess_data(label_namer=None)
     def boxplot(self, x, notch=None, sym=None, vert=None, whis=None,
                 positions=None, widths=None, patch_artist=None,
                 bootstrap=None, usermedians=None, conf_intervals=None,
@@ -3799,7 +3799,7 @@ def dopatch(xs, ys, **kwargs):
         return dict(whiskers=whiskers, caps=caps, boxes=boxes,
                     medians=medians, fliers=fliers, means=means)
 
-    @unpack_labeled_data(replace_names=["x", "y", "s", "linewidths",
+    @_preprocess_data(replace_names=["x", "y", "s", "linewidths",
                                         "edgecolors", "c", 'facecolor',
                                         'facecolors', 'color'],
                          label_namer="y")
@@ -4049,7 +4049,7 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
 
         return collection
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+    @_preprocess_data(replace_names=["x", "y"], label_namer="y")
     @docstring.dedent_interpd
     def hexbin(self, x, y, C=None, gridsize=100, bins=None,
                xscale='linear', yscale='linear', extent=None,
@@ -4553,7 +4553,7 @@ def quiverkey(self, *args, **kw):
     quiverkey.__doc__ = mquiver.QuiverKey.quiverkey_doc
 
     # args can by a combination if X, Y, U, V, C and all should be replaced
-    @unpack_labeled_data(replace_all_args=True, label_namer=None)
+    @_preprocess_data(replace_all_args=True, label_namer=None)
     def quiver(self, *args, **kw):
         if not self._hold:
             self.cla()
@@ -4565,12 +4565,12 @@ def quiver(self, *args, **kw):
     quiver.__doc__ = mquiver.Quiver.quiver_doc
 
     # args can by either Y or y1,y2,... and all should be replaced
-    @unpack_labeled_data(replace_all_args=True, label_namer=None)
+    @_preprocess_data(replace_all_args=True, label_namer=None)
     def stackplot(self, x, *args, **kwargs):
         return mstack.stackplot(self, x, *args, **kwargs)
     stackplot.__doc__ = mstack.stackplot.__doc__
 
-    @unpack_labeled_data(replace_names=["x", "y", "u", "v", "start_points"],
+    @_preprocess_data(replace_names=["x", "y", "u", "v", "start_points"],
                          label_namer=None)
     def streamplot(self, x, y, u, v, density=1, linewidth=None, color=None,
                    cmap=None, norm=None, arrowsize=1, arrowstyle='-|>',
@@ -4593,7 +4593,7 @@ def streamplot(self, x, y, u, v, density=1, linewidth=None, color=None,
     streamplot.__doc__ = mstream.streamplot.__doc__
 
     # args can be some combination of X, Y, U, V, C and all should be replaced
-    @unpack_labeled_data(replace_all_args=True, label_namer=None)
+    @_preprocess_data(replace_all_args=True, label_namer=None)
     @docstring.dedent_interpd
     def barbs(self, *args, **kw):
         """
@@ -4610,7 +4610,7 @@ def barbs(self, *args, **kw):
         self.autoscale_view()
         return b
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer=None,
+    @_preprocess_data(replace_names=["x", "y"], label_namer=None,
                         positional_parameter_names=["x", "y", "c"])
     @docstring.dedent_interpd
     def fill(self, *args, **kwargs):
@@ -4665,7 +4665,7 @@ def fill(self, *args, **kwargs):
         self.autoscale_view()
         return patches
 
-    @unpack_labeled_data(replace_names=["x", "y1", "y2", "where"],
+    @_preprocess_data(replace_names=["x", "y1", "y2", "where"],
                          label_namer=None)
     @docstring.dedent_interpd
     def fill_between(self, x, y1, y2=0, where=None, interpolate=False,
@@ -4820,7 +4820,7 @@ def get_interp_point(ind):
         self.autoscale_view()
         return collection
 
-    @unpack_labeled_data(replace_names=["y", "x1", "x2", "where"],
+    @_preprocess_data(replace_names=["y", "x1", "x2", "where"],
                          label_namer=None)
     @docstring.dedent_interpd
     def fill_betweenx(self, y, x1, x2=0, where=None,
@@ -4946,7 +4946,7 @@ def fill_betweenx(self, y, x1, x2=0, where=None,
         return collection
 
     #### plotting z(x,y): imshow, pcolor and relatives, contour
-    @unpack_labeled_data(label_namer=None)
+    @_preprocess_data(label_namer=None)
     @docstring.dedent_interpd
     def imshow(self, X, cmap=None, norm=None, aspect=None,
                interpolation=None, alpha=None, vmin=None, vmax=None,
@@ -5156,7 +5156,7 @@ def _pcolorargs(funcname, *args, **kw):
         C = cbook.safe_masked_invalid(C)
         return X, Y, C
 
-    @unpack_labeled_data(label_namer=None)
+    @_preprocess_data(label_namer=None)
     @docstring.dedent_interpd
     def pcolor(self, *args, **kwargs):
         """
@@ -5433,7 +5433,7 @@ def pcolor(self, *args, **kwargs):
         self.autoscale_view()
         return collection
 
-    @unpack_labeled_data(label_namer=None)
+    @_preprocess_data(label_namer=None)
     @docstring.dedent_interpd
     def pcolormesh(self, *args, **kwargs):
         """
@@ -5583,7 +5583,7 @@ def pcolormesh(self, *args, **kwargs):
         self.autoscale_view()
         return collection
 
-    @unpack_labeled_data(label_namer=None)
+    @_preprocess_data(label_namer=None)
     @docstring.dedent_interpd
     def pcolorfast(self, *args, **kwargs):
         """
@@ -5772,7 +5772,7 @@ def pcolorfast(self, *args, **kwargs):
         self.autoscale_view(tight=True)
         return ret
 
-    @unpack_labeled_data()
+    @_preprocess_data()
     def contour(self, *args, **kwargs):
         if not self._hold:
             self.cla()
@@ -5782,7 +5782,7 @@ def contour(self, *args, **kwargs):
         return contours
     contour.__doc__ = mcontour.QuadContourSet.contour_doc
 
-    @unpack_labeled_data()
+    @_preprocess_data()
     def contourf(self, *args, **kwargs):
         if not self._hold:
             self.cla()
@@ -5825,7 +5825,7 @@ def table(self, **kwargs):
 
     #### Data analysis
 
-    @unpack_labeled_data(replace_names=["x", 'weights'], label_namer="x")
+    @_preprocess_data(replace_names=["x", 'weights'], label_namer="x")
     @docstring.dedent_interpd
     def hist(self, x, bins=None, range=None, normed=False, weights=None,
              cumulative=False, bottom=None, histtype='bar', align='mid',
@@ -6391,7 +6391,7 @@ def _normalize_input(inp, ename='input'):
         else:
             return n, bins, cbook.silent_list('Lists of Patches', patches)
 
-    @unpack_labeled_data(replace_names=["x", "y", "weights"], label_namer=None)
+    @_preprocess_data(replace_names=["x", "y", "weights"], label_namer=None)
     @docstring.dedent_interpd
     def hist2d(self, x, y, bins=10, range=None, normed=False, weights=None,
                cmin=None, cmax=None, **kwargs):
@@ -6485,7 +6485,7 @@ def hist2d(self, x, y, bins=10, range=None, normed=False, weights=None,
 
         return h, xedges, yedges, pc
 
-    @unpack_labeled_data(replace_names=["x"], label_namer=None)
+    @_preprocess_data(replace_names=["x"], label_namer=None)
     @docstring.dedent_interpd
     def psd(self, x, NFFT=None, Fs=None, Fc=None, detrend=None,
             window=None, noverlap=None, pad_to=None,
@@ -6610,7 +6610,7 @@ def psd(self, x, NFFT=None, Fs=None, Fc=None, detrend=None,
         else:
             return pxx, freqs, line
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+    @_preprocess_data(replace_names=["x", "y"], label_namer="y")
     @docstring.dedent_interpd
     def csd(self, x, y, NFFT=None, Fs=None, Fc=None, detrend=None,
             window=None, noverlap=None, pad_to=None,
@@ -6722,7 +6722,7 @@ def csd(self, x, y, NFFT=None, Fs=None, Fc=None, detrend=None,
         else:
             return pxy, freqs, line
 
-    @unpack_labeled_data(replace_names=["x"], label_namer=None)
+    @_preprocess_data(replace_names=["x"], label_namer=None)
     @docstring.dedent_interpd
     def magnitude_spectrum(self, x, Fs=None, Fc=None, window=None,
                            pad_to=None, sides=None, scale=None,
@@ -6822,7 +6822,7 @@ def magnitude_spectrum(self, x, Fs=None, Fc=None, window=None,
 
         return spec, freqs, lines[0]
 
-    @unpack_labeled_data(replace_names=["x"], label_namer=None)
+    @_preprocess_data(replace_names=["x"], label_namer=None)
     @docstring.dedent_interpd
     def angle_spectrum(self, x, Fs=None, Fc=None, window=None,
                        pad_to=None, sides=None, **kwargs):
@@ -6900,7 +6900,7 @@ def angle_spectrum(self, x, Fs=None, Fc=None, window=None,
 
         return spec, freqs, lines[0]
 
-    @unpack_labeled_data(replace_names=["x"], label_namer=None)
+    @_preprocess_data(replace_names=["x"], label_namer=None)
     @docstring.dedent_interpd
     def phase_spectrum(self, x, Fs=None, Fc=None, window=None,
                        pad_to=None, sides=None, **kwargs):
@@ -6978,7 +6978,7 @@ def phase_spectrum(self, x, Fs=None, Fc=None, window=None,
 
         return spec, freqs, lines[0]
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer=None)
+    @_preprocess_data(replace_names=["x", "y"], label_namer=None)
     @docstring.dedent_interpd
     def cohere(self, x, y, NFFT=256, Fs=2, Fc=0, detrend=mlab.detrend_none,
                window=mlab.window_hanning, noverlap=0, pad_to=None,
@@ -7046,7 +7046,7 @@ def cohere(self, x, y, NFFT=256, Fs=2, Fc=0, detrend=mlab.detrend_none,
 
         return cxy, freqs
 
-    @unpack_labeled_data(replace_names=["x"], label_namer=None)
+    @_preprocess_data(replace_names=["x"], label_namer=None)
     @docstring.dedent_interpd
     def specgram(self, x, NFFT=None, Fs=None, Fc=None, detrend=None,
                  window=None, noverlap=None,
@@ -7364,7 +7364,7 @@ def matshow(self, Z, **kwargs):
                                                  integer=True))
         return im
 
-    @unpack_labeled_data(replace_names=["dataset"], label_namer=None)
+    @_preprocess_data(replace_names=["dataset"], label_namer=None)
     def violinplot(self, dataset, positions=None, vert=True, widths=0.5,
                    showmeans=False, showextrema=True, showmedians=False,
                    points=100, bw_method=None):
diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
index 0216ccb9c501..5556a65d4c09 100644
--- a/lib/matplotlib/cbook.py
+++ b/lib/matplotlib/cbook.py
@@ -16,7 +16,7 @@
 
 import datetime
 import errno
-from functools import reduce
+import functools
 import glob
 import gzip
 import io
@@ -1758,7 +1758,7 @@ def delete_masked_points(*args):
             except:  # Fixme: put in tuple of possible exceptions?
                 pass
     if len(masks):
-        mask = reduce(np.logical_and, masks)
+        mask = functools.reduce(np.logical_and, masks)
         igood = mask.nonzero()[0]
         if len(igood) < nrecs:
             for i, x in enumerate(margs):
@@ -2445,6 +2445,14 @@ def safe_first_element(obj):
     return next(iter(obj))
 
 
+def sanitize_sequence(data):
+    """Converts dictview object to list
+    """
+    if six.PY3 and isinstance(data, collections.abc.MappingView):
+        return list(data)
+    return data
+
+
 def normalize_kwargs(kw, alias_mapping=None, required=(), forbidden=(),
                      allowed=None):
     """Helper function to normalize kwarg inputs
diff --git a/lib/matplotlib/tests/test_cbook.py b/lib/matplotlib/tests/test_cbook.py
index 093220ab659e..5077baaa4769 100644
--- a/lib/matplotlib/tests/test_cbook.py
+++ b/lib/matplotlib/tests/test_cbook.py
@@ -332,6 +332,18 @@ def dummy(self):
         pass
 
 
+def test_sanitize_sequence():
+    d = {'a': 1, 'b': 2, 'c': 3}
+    k = ['a', 'b', 'c']
+    v = [1, 2, 3]
+    i = [('a', 1), ('b', 2), ('c', 3)]
+    assert k == sorted(cbook.sanitize_sequence(d.keys()))
+    assert v == sorted(cbook.sanitize_sequence(d.values()))
+    assert i == sorted(cbook.sanitize_sequence(d.items()))
+    assert i == cbook.sanitize_sequence(i)
+    assert k == cbook.sanitize_sequence(k)
+
+
 def _kwarg_norm_helper(inp, expected, kwargs_to_norm, warn_count=0):
 
     with warnings.catch_warnings(record=True) as w:
diff --git a/lib/matplotlib/tests/test_labeled_data_unpacking.py b/lib/matplotlib/tests/test_preprocess_data.py
similarity index 89%
rename from lib/matplotlib/tests/test_labeled_data_unpacking.py
rename to lib/matplotlib/tests/test_preprocess_data.py
index d07d481b1f57..6231e7c7c342 100644
--- a/lib/matplotlib/tests/test_labeled_data_unpacking.py
+++ b/lib/matplotlib/tests/test_preprocess_data.py
@@ -14,7 +14,7 @@
 
 from ..testing import assert_produces_warning
 
-from .. import unpack_labeled_data
+from .. import _preprocess_data
 
 
 # Notes on testing the plotting functions itself
@@ -24,13 +24,13 @@
 
 
 # these two get used in multiple tests, so define them here
-@unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+@_preprocess_data(replace_names=["x", "y"], label_namer="y")
 def plot_func(ax, x, y, ls="x", label=None, w="xyz"):
     return ("x: %s, y: %s, ls: %s, w: %s, label: %s" % (
         list(x), list(y), ls, w, label))
 
 
-@unpack_labeled_data(replace_names=["x", "y"], label_namer="y",
+@_preprocess_data(replace_names=["x", "y"], label_namer="y",
                      positional_parameter_names=["x", "y", "ls", "label", "w"])
 def plot_func_varags(ax, *args, **kwargs):
     all_args = [None, None, "x", None, "xyz"]
@@ -59,48 +59,48 @@ def func_kwargs(ax, x, y, **kwargs): pass
     def func_no_ax_args(*args, **kwargs): pass
 
     # this is ok
-    unpack_labeled_data(replace_names=["x", "y"])(func)
-    unpack_labeled_data(replace_names=["x", "y"])(func_kwargs)
+    _preprocess_data(replace_names=["x", "y"])(func)
+    _preprocess_data(replace_names=["x", "y"])(func_kwargs)
     # this has "enough" information to do all the replaces
-    unpack_labeled_data(replace_names=["x", "y"])(func_args)
+    _preprocess_data(replace_names=["x", "y"])(func_args)
 
     # no positional_parameter_names but needed due to replaces
     def f():
         # z is unknown
-        unpack_labeled_data(replace_names=["x", "y", "z"])(func_args)
+        _preprocess_data(replace_names=["x", "y", "z"])(func_args)
 
     assert_raises(AssertionError, f)
 
     def f():
-        unpack_labeled_data(replace_names=["x", "y"])(func_no_ax_args)
+        _preprocess_data(replace_names=["x", "y"])(func_no_ax_args)
 
     assert_raises(AssertionError, f)
 
     # no replacements at all -> all ok...
-    unpack_labeled_data(replace_names=[], label_namer=None)(func)
-    unpack_labeled_data(replace_names=[], label_namer=None)(func_args)
-    unpack_labeled_data(replace_names=[], label_namer=None)(func_kwargs)
-    unpack_labeled_data(replace_names=[], label_namer=None)(func_no_ax_args)
+    _preprocess_data(replace_names=[], label_namer=None)(func)
+    _preprocess_data(replace_names=[], label_namer=None)(func_args)
+    _preprocess_data(replace_names=[], label_namer=None)(func_kwargs)
+    _preprocess_data(replace_names=[], label_namer=None)(func_no_ax_args)
 
     # label namer is unknown
     def f():
-        unpack_labeled_data(label_namer="z")(func)
+        _preprocess_data(label_namer="z")(func)
 
     assert_raises(AssertionError, f)
 
     def f():
-        unpack_labeled_data(label_namer="z")(func_args)
+        _preprocess_data(label_namer="z")(func_args)
 
     assert_raises(AssertionError, f)
     # but "ok-ish", if func has kwargs -> will show up at runtime :-(
-    unpack_labeled_data(label_namer="z")(func_kwargs)
-    unpack_labeled_data(label_namer="z")(func_no_ax_args)
+    _preprocess_data(label_namer="z")(func_kwargs)
+    _preprocess_data(label_namer="z")(func_no_ax_args)
 
 
 def test_label_problems_at_runtime():
     """Tests for behaviour which would actually be nice to get rid of."""
 
-    @unpack_labeled_data(label_namer="z")
+    @_preprocess_data(label_namer="z")
     def func(*args, **kwargs):
         pass
 
@@ -117,7 +117,7 @@ def f():
     def real_func(x, y):
         pass
 
-    @unpack_labeled_data(label_namer="x")
+    @_preprocess_data(label_namer="x")
     def func(*args, **kwargs):
         real_func(**kwargs)
 
@@ -209,7 +209,7 @@ def test_function_call_replace_all():
     """Test without a "replace_names" argument, all vars should be replaced"""
     data = {"a": [1, 2], "b": [8, 9], "x": "xyz"}
 
-    @unpack_labeled_data(label_namer="y")
+    @_preprocess_data(label_namer="y")
     def func_replace_all(ax, x, y, ls="x", label=None, w="NOT"):
         return "x: %s, y: %s, ls: %s, w: %s, label: %s" % (
             list(x), list(y), ls, w, label)
@@ -230,7 +230,7 @@ def func_replace_all(ax, x, y, ls="x", label=None, w="NOT"):
         func_replace_all(None, x="a", y="b", w="x", label="text", data=data),
         "x: [1, 2], y: [8, 9], ls: x, w: xyz, label: text")
 
-    @unpack_labeled_data(label_namer="y")
+    @_preprocess_data(label_namer="y")
     def func_varags_replace_all(ax, *args, **kwargs):
         all_args = [None, None, "x", None, "xyz"]
         for i, v in enumerate(args):
@@ -270,7 +270,7 @@ def func_varags_replace_all(ax, *args, **kwargs):
 def test_no_label_replacements():
     """Test with "label_namer=None" -> no label replacement at all"""
 
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer=None)
+    @_preprocess_data(replace_names=["x", "y"], label_namer=None)
     def func_no_label(ax, x, y, ls="x", label=None, w="xyz"):
         return "x: %s, y: %s, ls: %s, w: %s, label: %s" % (
             list(x), list(y), ls, w, label)
@@ -287,7 +287,7 @@ def func_no_label(ax, x, y, ls="x", label=None, w="xyz"):
 
 
 def test_more_args_than_pos_parameter():
-    @unpack_labeled_data(replace_names=["x", "y"], label_namer="y")
+    @_preprocess_data(replace_names=["x", "y"], label_namer="y")
     def func(ax, x, y, z=1):
         pass
 
@@ -314,7 +314,7 @@ def funcy(ax, *args, **kwargs):
         return "x: %s, y: %s, ls: %s, w: %s, label: %s" % (
             list(x), list(y), ls, w, label)
 
-    func = unpack_labeled_data(replace_all_args=True, replace_names=["w"],
+    func = _preprocess_data(replace_all_args=True, replace_names=["w"],
                                label_namer="y")(funcy)
 
     assert_equal(func(None, "a", "b", w="x", label="", data=data),
@@ -322,7 +322,7 @@ def funcy(ax, *args, **kwargs):
     assert_equal(func(None, "a", "b", w="x", label="text", data=data),
                  "x: [1, 2], y: [8, 9], ls: x, w: xyz, label: text")
 
-    func2 = unpack_labeled_data(replace_all_args=True, replace_names=["w"],
+    func2 = _preprocess_data(replace_all_args=True, replace_names=["w"],
                                 label_namer="y",
                                 positional_parameter_names=["x", "y", "ls",
                                                             "label", "w"])(
@@ -337,7 +337,7 @@ def funcy(ax, *args, **kwargs):
 
 
 def test_docstring_addition():
-    @unpack_labeled_data()
+    @_preprocess_data()
     def funcy(ax, *args, **kwargs):
         """Funcy does nothing"""
         pass
@@ -348,7 +348,7 @@ def funcy(ax, *args, **kwargs):
     assert_not_regex(funcy.__doc__,
                               r".*All arguments with the following names: .*")
 
-    @unpack_labeled_data(replace_all_args=True, replace_names=[])
+    @_preprocess_data(replace_all_args=True, replace_names=[])
     def funcy(ax, x, y, z, bar=None):
         """Funcy does nothing"""
         pass
@@ -359,7 +359,7 @@ def funcy(ax, x, y, z, bar=None):
     assert_not_regex(funcy.__doc__,
                               r".*All arguments with the following names: .*")
 
-    @unpack_labeled_data(replace_all_args=True, replace_names=["bar"])
+    @_preprocess_data(replace_all_args=True, replace_names=["bar"])
     def funcy(ax, x, y, z, bar=None):
         """Funcy does nothing"""
         pass
@@ -370,7 +370,7 @@ def funcy(ax, x, y, z, bar=None):
     assert_not_regex(funcy.__doc__,
                               r".*All positional and all keyword arguments\.")
 
-    @unpack_labeled_data(replace_names=["x", "bar"])
+    @_preprocess_data(replace_names=["x", "bar"])
     def funcy(ax, x, y, z, bar=None):
         """Funcy does nothing"""
         pass
@@ -389,7 +389,7 @@ def test_positional_parameter_names_as_function():
     # Also test the _plot_arg_replacer for plot...
     from matplotlib.axes._axes import _plot_args_replacer
 
-    @unpack_labeled_data(replace_names=["x", "y"],
+    @_preprocess_data(replace_names=["x", "y"],
                          positional_parameter_names=_plot_args_replacer)
     def funcy(ax, *args, **kwargs):
         return "{args} | {kwargs}".format(args=args, kwargs=kwargs)