*False* values in *where*
            will not result in filling.  Both sides of the *True* position
            remain unfilled due to the adjacent *False* values.

        interpolate : bool, default: False
            This option is only relevant if *where* is used and the two curves
            are crossing each other.

            Semantically, *where* is often used for *{dep}1* > *{dep}2* or
            similar.  By default, the nodes of the polygon defining the filled
            region will only be placed at the positions in the *{ind}* array.
            Such a polygon cannot describe the above semantics close to the
            intersection.  The {ind}-sections containing the intersection are
            simply clipped.

            Setting *interpolate* to *True* will calculate the actual
            intersection point and extend the filled region up to this point.

        step : {{'pre', 'post', 'mid'}}, optional
            Define *step* if the filling should be a step function,
            i.e. constant in between *{ind}*.  The value determines where the
            step will occur:

            - 'pre': The y value is continued constantly to the left from
              every *x* position, i.e. the interval ``(x[i-1], x[i]]`` has the
              value ``y[i]``.
            - 'post': The y value is continued constantly to the right from
              every *x* position, i.e. the interval ``[x[i], x[i+1])`` has the
              value ``y[i]``.
            - 'mid': Steps occur half-way between the *x* positions.

        Returns
        -------
        `.PolyCollection`
            A `.PolyCollection` containing the plotted polygons.

        Other Parameters
        ----------------
        data : indexable object, optional
            DATA_PARAMETER_PLACEHOLDER

        **kwargs
            All other keyword arguments are passed on to `.PolyCollection`.
            They control the `.Polygon` properties:

            %(PolyCollection:kwdoc)s

        See Also
        --------
        fill_between : Fill between two sets of y-values.
        fill_betweenx : Fill between two sets of x-values.
        r$