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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_filter(filters, n, eigenvalues, sum, title, ax, **kwargs):
 r"""Plot the spectral response of a filter bank. Parameters n : int Number of points where the filters are evaluated. eigenvalues : boolean Whether to show the eigenvalues of the graph Laplacian. The eigenvalues should have been computed with :meth:`~pygsp.graphs.Graph.compute_fourier_basis`. By default, the eigenvalues are shown if they are available. sum : boolean Whether to plot the sum of the squared magnitudes of the filters. Default True if there is multiple filters. title : str Title of the figure. ax : :class:`matplotlib.axes.Axes` Axes where to draw the graph. Optional, created if not passed. Only available with the matplotlib backend. kwargs : dict Additional parameters passed to the matplotlib plot function. Useful for example to change the linewidth, linestyle, or set a label. Only available with the matplotlib backend. Returns ------- fig : :class:`matplotlib.figure.Figure` The figure the plot belongs to. Only with the matplotlib backend. ax : :class:`matplotlib.axes.Axes` The axes the plot belongs to. Only with the matplotlib backend. Notes ----- This function is only implemented for the matplotlib backend at the moment. Examples -------- """


    if eigenvalues is None:
        eigenvalues = (filters.G._e is not None)

    if sum is None:
        sum = filters.n_filters > 1

    if title is None:
        title = repr(filters)

    return _plt_plot_filter(filters, n=n, eigenvalues=eigenvalues, sum=sum,
                            title=title, ax=ax, **kwargs)