code: def background_gradient(self, cmap='PuBu', low=0, high=0, axis=0,
                              subset=None, text_color_threshold=0.408):
          
          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
docs: 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.