code: def plot_correlation(self, freq=None, title=None,
                           figsize=(12, 6), **kwargs):
          
          if title is None:
              title = self._get_default_plot_title(
                  freq, 'Return Correlation Matrix')
  
          rets = self._get_series(freq).to_returns().dropna()
          return rets.plot_corr_heatmap(title=title, figsize=figsize, **kwargs)
docs: Utility function to plot correlations.
  
          Args:
              * freq (str): Pandas data frequency alias string
              * title (str): Plot title
              * figsize (tuple (x,y)): figure size
              * kwargs: passed to Pandas' plot_corr_heatmap function