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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_scatter_matrix(self, freq=None, title=None, figsize=(10, 10), **kwargs):
 """ Wrapper around pandas' scatter_matrix. Args: * freq (str):
 Data frequency used for display purposes. Refer to pandas docs for valid freq strings. * figsize ((x,y)):
 figure size * title (str):
 Title if default not appropriate * kwargs: passed to pandas' scatter_matrix method """

        if title is None:
            title = self._get_default_plot_title(
                freq, 'Return Scatter Matrix')

        plt.figure()
        ser = self._get_series(freq).to_returns().dropna()
        pd.scatter_matrix(ser, figsize=figsize, **kwargs)
        return plt.suptitle(title)