code: def add_extra_headers(self, sample_names):
          
          if not sample_names:
              return []
          full_headers = list(self.orient_data[sample_names[0]].keys())
          add_ons = []
          for head in full_headers:
              if head not in self.header_names:
                  add_ons.append((head, head))
          return add_ons
docs: If there are samples, add any additional keys they might use
          to supplement the default headers.
          Return the headers headers for adding, with the format:
          [(header_name, header_display_name), ....]