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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def plot(self, minx=-1.5, maxx=1.2, miny=-0.2, maxy=2, **kwargs):
 """Helper function to plot the Muller potential """

        import matplotlib.pyplot as pp
        grid_width = max(maxx-minx, maxy-miny) / 200.0

        ax = kwargs.pop('ax', None)

        xx, yy = np.mgrid[minx:maxx:grid_width, miny:maxy:grid_width]
        V = self.potential(xx, yy)
        # clip off any values greater than 200, since they mess up
        # the color scheme
        if ax is None:
            ax = pp

        ax.contourf(xx, yy, V.clip(max=200), 40, **kwargs)