arnings
--------
This method is experimental as of 3.1, and the API may change.

Parameters
----------
location : {'top', 'bottom', 'left', 'right'} or float
    The position to put the secondary axis.  Strings can be 'top' or
    'bottom' for orientation='x' and 'right' or 'left' for
    orientation='y'. A float indicates the relative position on the
    parent axes to put the new axes, 0.0 being the bottom (or left)
    and 1.0 being the top (or right).

functions : 2-tuple of func, or Transform with an inverse

    If a 2-tuple of functions, the user specifies the transform
    function and its inverse.  i.e.
    ``functions=(lambda x: 2 / x, lambda x: 2 / x)`` would be an
    reciprocal transform with a factor of 2. Both functions must accept
    numpy arrays as input.

    The user can also directly supply a subclass of
    `.transforms.Transform` so long as it has an inverse.

    See :doc:`/gallery/subplots_axes_and_figures/secondary_axis`
    for examples of making these conversions.

Returns
-------
ax : axes._secondary_axes.SecondaryAxis

Other Parameters
----------------
**kwargs : `~matplotlib.axes.Axes` properties.
    Other miscellaneous axes parameters.
)