Color the background in a gradient according to
        the data in each column (optionally row).

        Requires matplotlib.

        Parameters
        ----------
        cmap : str or colormap
            matplotlib colormap
        low, high : float
            compress the range by these values.
        axis : {0 or 'index', 1 or 'columns', None}, default 0
            apply to each column (``axis=0`` or ``'index'``), to each row
            (``axis=1`` or ``'columns'``), or to the entire DataFrame at once
            with ``axis=None``.
        subset : IndexSlice
            a valid slice for ``data`` to limit the style application to.
        text_color_threshold : float or int
            luminance threshold for determining text color. Facilitates text
            visibility across varying background colors. From 0 to 1.
            0 = all text is dark colored, 1 = all text is light colored.

            .. versionadded:: 0.24.0

        Returns
        -------
        self : Styler

        Raises
        ------
        ValueError
            If ``text_color_threshold`` is not a value from 0 to 1.

        Notes
        -----
        Set ``text_color_threshold`` or tune ``low`` and ``high`` to keep the
        text legible by not using the entire range of the color map. The range
        of the data is extended by ``low * (x.max() - x.min())`` and ``high *
        (x.max() - x.min())`` before normalizing.

def background_gradient(self, cmap='PuBu', low=0, high=0, axis=0,
                            subset=None, text_color_threshold=0.408):
        """
        Color the background in a gradient according to
        the data in each column (optionally row).

        Requires matplotlib.

        Parameters
        ----------
        cmap : str or colormap
            matplotlib colormap
        low, high : float
            compress the range by these values.
        axis : {0 or 'index', 1 or 'columns', None}, default 0
            apply to each column (``axis=0`` or ``'index'``), to each row
            (``axis=1`` or ``'columns'``), or to the entire DataFrame at once
            with ``axis=None``.
        subset : IndexSlice
            a valid slice for ``data`` to limit the style application to.
        text_color_threshold : float or int
            luminance threshold for determining text color. Facilitates text
            visibility across varying background colors. From 0 to 1.
            0 = all text is dark colored, 1 = all text is light colored.

            .. versionadded:: 0.24.0

        Returns
        -------
        self : Styler

        Raises
        ------
        ValueError
            If ``text_color_threshold`` is not a value from 0 to 1.

        Notes
        -----
        Set ``text_color_threshold`` or tune ``low`` and ``high`` to keep the
        text legible by not using the entire range of the color map. The range
        of the data is extended by ``low * (x.max() - x.min())`` and ``high *
        (x.max() - x.min())`` before normalizing.
        """
        subset = _maybe_numeric_slice(self.data, subset)
        subset = _non_reducing_slice(subset)
        self.apply(self._background_gradient, cmap=cmap, subset=subset,
                   axis=axis, low=low, high=high,
                   text_color_threshold=text_color_threshold)
        return self