code: def _longest_contig(self, contig_set, contig_lengths):
          '''Returns the name of the longest contig, from the set of names contig_set. contig_lengths
             is expected to be a dictionary of contig name => length.'''
          longest_name = None
          max_length = -1
          for name in contig_set:
              if contig_lengths[name] > max_length:
                  longest_name = name
                  max_length = contig_lengths[name]
          assert max_length != -1
          assert longest_name is not None
          return longest_namf _longest_contig(self, contig_set, contig_lengths):
          '''Returns the name of the longest contig, from the set of names contig_set. contig_lengths
             is expected to be a dictionary of contig name => length.'''
          longest_name = None
          max_length = -1
          for name in contig_set:
              if contig_lengths[name] > max_length:
                  longest_name = name
                  max_length = contig_lengths[name]
          assert max_length != -1
          assert longest_name is not None
          return longest_name
docs: Returns the name of the longest contig, from the set of names contig_set. contig_lengths
             is expected to be a dictionary of contig name => length.