def rename_axis(self, mapper, axis, copy=True, level=None):
obj = self.copy(deep=copy)<EOL>obj.set_axis(axis, _transform_index(self.axes[axis], mapper, level))<EOL>return obj<EOL>
Rename one of axes.

Parameters
----------
mapper : unary callable
axis : int
copy : boolean, default True
level : int, default None