saved.  If 'tight', try to figure out the tight bbox of the figure.

        pad_inches : float, default: :rc:`savefig.pad_inches`
            Amount of padding around the figure when *bbox_inches* is 'tight'.

        bbox_extra_artists : list of `~matplotlib.artist.Artist`, optional
            A list of extra artists that will be considered when the
            tight bbox is calculated.

        backend : str, optional
            Use a non-default backend to render the file, e.g. to render a
            png file with the "cairo" backend rather than the default "agg",
            or a pdf file with the "pgf" backend rather than the default
            "pdf".  Note that the default backend is normally sufficient.  See
            :ref:`the-builtin-backends` for a list of valid backends for each
            file format.  Custom backends can be referenced as "module://...".
        Nrž