Writes the phase diagram to an image in a stream.

        Args:
            stream:
                stream to write to. Can be a file stream or a StringIO stream.
            image_format
                format for image. Can be any of matplotlib supported formats.
                Defaults to svg for best results for vector graphics.
            \\*\\*kwargs: Pass through to get_plot functino.

def write_image(self, stream, image_format="svg", **kwargs):
        """
        Writes the phase diagram to an image in a stream.

        Args:
            stream:
                stream to write to. Can be a file stream or a StringIO stream.
            image_format
                format for image. Can be any of matplotlib supported formats.
                Defaults to svg for best results for vector graphics.
            \\*\\*kwargs: Pass through to get_plot functino.
        """
        plt = self.get_plot(**kwargs)

        f = plt.gcf()
        f.set_size_inches((12, 10))

        plt.savefig(stream, format=image_format)