code: def _add_sequence(self, pdbID, chainID, sequence):
          '''This is a 'private' function. If you call it directly, call _find_identical_sequences() afterwards to update identical_sequences.'''
          pdbID = pdbID.upper()
          self[pdbID] = self.get(pdbID, {})
          self[pdbID][chainID] = sequence
          self.sequences.append((pdbID, chainID, sequence))
          if not self.unique_sequences.get(sequence):
              self.unique_sequences[sequence] = visible_colors[len(self.unique_sequences) % len(visible_colors)]
          self.identical_sequences = Nonf _add_sequence(self, pdbID, chainID, sequence):
          '''This is a 'private' function. If you call it directly, call _find_identical_sequences() afterwards to update identical_sequences.'''
          pdbID = pdbID.upper()
          self[pdbID] = self.get(pdbID, {})
          self[pdbID][chainID] = sequence
          self.sequences.append((pdbID, chainID, sequence))
          if not self.unique_sequences.get(sequence):
              self.unique_sequences[sequence] = visible_colors[len(self.unique_sequences) % len(visible_colors)]
          self.identical_sequences = None
docs: This is a 'private' function. If you call it directly, call _find_identical_sequences() afterwards to update identical_sequences.