code: def plot_correlation_heatmap(self):
          
          data = None
          corr_type = None
          correlation_type = getattr(config, 'rna_seqc' ,{}).get('default_correlation', 'spearman')
          if self.rna_seqc_spearman is not None and correlation_type != 'pearson':
              data = self.rna_seqc_spearman
              corr_type = 'Spearman'
          elif self.rna_seqc_pearson is not None:
              data = self.rna_seqc_pearson
              corr_type = 'Pearson'
          if data is not None:
              pconfig = {
                  'id': 'rna_seqc_correlation_heatmap',
                  'title': 'RNA-SeQC: {} Sample Correlation'.format(corr_type)
              }
              self.add_section (
                  name = '{} Correlation'.format(corr_type),
                  anchor = 'rseqc-rna_seqc_correlation',
                  plot = heatmap.plot(data[1], data[0], data[0], pconfig)
              )
docs: Return HTML for correlation heatmap