docs: def lines(self):
          '''Display the system bonds as lines.
  
          '''
          if "bonds" not in self.topology:
              return
  
          bond_start, bond_end = zip(*self.topology['bonds'])
          bond_start = np.array(bond_start)
          bond_end = np.array(bond_end)
  
          color_array = np.array([get_atom_color(t) for t in self.topology['atom_types']])
          lines = self.add_representation('lines', {'startCoords': self.coordinates[bond_start],
                                                    'endCoords': self.coordinates[bond_end],
                                                    'startColors': color_array[bond_start].tolist(),
                                                    'endColors': color_array[bond_end].tolist()})
  
          def update(self=self, lines=lines):
              bond_start, bond_end = zip(*self.topology['bonds'])
              bond_start = np.array(bond_start)
              bond_end = np.array(bond_end)
  
              self.update_representation(lines, {'startCoords': self.coordinates[bond_start],
                                                   'endCoords': self.coordinates[bond_end]})
          self.update_callbacks.append(update)
          self.autozoom(self.coordinates)