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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 heatmap(self, partition=None, cmap=CM.Blues):
 """ Plots a visual representation of a distance matrix """


        if isinstance(self.dm, DistanceMatrix):
            length = self.dm.values.shape[0]
        else:
            length = self.dm.shape[0]
        datamax = float(np.abs(self.dm).max())
        fig = plt.figure()
        ax = fig.add_subplot(111)
        ticks_at = [0, 0.5 * datamax, datamax]
        if partition:
            sorting = flatten_list(partition.get_membership())
            self.dm = self.dm.reorder(sorting)
        cax = ax.imshow(
            self.dm.values,
            interpolation='nearest',
            origin='lower',
            extent=[0., length, 0., length],
            vmin=0,
            vmax=datamax,
            cmap=cmap,
        )
        cbar = fig.colorbar(cax, ticks=ticks_at, format='%1.2g')
        cbar.set_label('Distance')
        return fig