Draw watermark

        Parameters
        ----------
        figure : Matplotlib.figure.Figure
            Matplolib figure on which to draw

def draw(self, figure):
        """
        Draw watermark

        Parameters
        ----------
        figure : Matplotlib.figure.Figure
            Matplolib figure on which to draw
        """
        X = mimage.imread(self.filename)
        figure.figimage(X, **self.kwargs)