matplotlib
diff --git a/‎lib/matplotlib/tests/test_ticker.py‎
Lines changed: 0 additions & 1 deletion b/‎lib/matplotlib/tests/test_ticker.py‎
Lines changed: 0 additions & 1 deletion
diff --git a/‎lib/matplotlib/ticker.py‎
Lines changed: 14 additions & 16 deletions b/‎lib/matplotlib/ticker.py‎
Lines changed: 14 additions & 16 deletions
@@ -1051,7 +1051,6 @@ class TestFuncFormatter:
              ("format 2 inputs",
                 ("{}+{}!".format, [2, 3], "2+3!"))]
     ids, data = zip(*tests)
-
     @pytest.mark.parametrize("func, args, expected", data, ids=ids)
     def test_arguments(self, func, args, expected):
         assert expected == mticker.FuncFormatter(func)(*args)
 
@@ -171,7 +171,6 @@
 import math
 import string
 import types
-import warnings
 from numbers import Integral
 
 import numpy as np
@@ -386,25 +385,23 @@ class FuncFormatter(Formatter):
      the corresponding tick label.
     """
     def __init__(self, func):
+        self.func = func
+
         if not isinstance(func, types.BuiltinFunctionType):
-            nargs = len(inspect.signature(func).parameters)
-        elif (func.__name__ == 'format'):
+            self.nargs = len(inspect.signature(func).parameters)
+        elif (isinstance(getattr(func, "__self__"), str) and 
+                (getattr(func, "__name__", "") == "format")):
             #check if there's a format spec
-            nargs = len([(_, _, fs, _) for (_, _, fs, _)
-                         in string.Formatter().parse(func.__self__)
-                         if fs is not None])
+            self.nargs = len([(_, _, fs, _) for (_, _, fs, _) 
+                              in string.Formatter().parse(func.__self__)
+                              if fs is not None])
         else:
             #finding argcount for other builtins is a mess
-            nargs = 2
-            raise warnings.warn(f"{func.__name__} is not supported "
-                                 "and may not work as expected")
-
-        if nargs == 1:
-            self.func = lambda x, pos: func(x)
-        elif nargs == 2:
-            self.func = func
-        else:
-            raise TypeError(f"{func.__name__} takes {nargs} arguments. "
+            self.nargs = 2
+            cbook._warn_external(f"{func.__name__} is not supported "
+                                  "and may not work as expected")
+        if self.nargs not in [1, 2]:
+            raise TypeError(f"{func.__name__} takes {self.nargs} arguments. "
                              "FuncFormatter functions take at most 2: "
                              "x (required), pos (optional).")
 
@@ -414,6 +411,7 @@ def __call__(self, x, pos=None):
 
         *x* and *pos* are passed through as-is.
         """
+        if self.nargs == 1: return self.func(x)
         return self.func(x, pos)