Improve error message.

chahak13 · chahak13 · commit b4b3235e337d · 2022-12-17T10:58:44.000+05:30
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -1458,7 +1458,7 @@ def _contour_args(self, args, kwargs):
         elif (("X" in kwargs) ^ ("Y" in kwargs)) and "Z" in kwargs:
             raise TypeError(
                 "Both or neither 'X' and 'Y' may be passed as kwargs. "
-                "Passing only one of the two is not allowed."
+                "Passing only one of 'X' or 'Y' is not allowed."
             )
         elif "Z" in kwargs:
             z = ma.asarray(kwargs.pop("Z"), dtype=np.float64)
