code: def marshall_lines(self, collector):
          
  
          if isinstance(collector, collectors.Counter):
              exec_method = self._format_counter
          elif isinstance(collector, collectors.Gauge):
              exec_method = self._format_gauge
          elif isinstance(collector, collectors.Summary):
              exec_method = self._format_summary
          else:
              raise TypeError("Not a valid object format")
  
          # create headers
          help_header = TextFormat.HELP_FMT.format(name=collector.name,
                                                   help_text=collector.help_text)
  
          type_header = TextFormat.TYPE_FMT.format(name=collector.name,
                                                   value_type=collector.REPR_STR)
  
          # Prepare start headers
          lines = [help_header, type_header]
  
          for i in collector.get_all():
              r = exec_method(i, collector.name, collector.const_labels)
  
              # Check if it returns one or multiple lines
              if not isinstance(r, str) and isinstance(r, collections.Iterable):
                  lines.extend(r)
              else:
                  lines.append(r)
  
          return lines
docs: Marshalls a collector and returns the storage/transfer format in
              a tuple, this tuple has reprensentation format per element.