docs: def line_ribbon(self):
          '''Display the protein secondary structure as a white lines that passes through the
             backbone chain.
  
          '''
          # Control points are the CA (C alphas)
          backbone = np.array(self.topology['atom_names']) == 'CA'
          smoothline = self.add_representation('smoothline', {'coordinates': self.coordinates[backbone],
                                                              'color': 0xffffff})
  
          def update(self=self, smoothline=smoothline):
              self.update_representation(smoothline, {'coordinates': self.coordinates[backbone]})
          self.update_callbacks.append(update)
  
          self.autozoom(self.coordinates)