code: def minor_residues_per_turn(self, minor_repeat=None):
          
          if minor_repeat is None:
              minor_rpt = _helix_parameters[self.minor_helix_type][0]
          else:
              # precession angle in radians
              precession = self.curve.t_from_arc_length(
                  minor_repeat * self.minor_rise_per_residue)
              if self.orientation == -1:
                  precession = -precession
              if self.major_handedness != self.minor_handedness:
                  precession = -precession
              minor_rpt = ((minor_repeat * numpy.pi * 2) /
                           ((2 * numpy.pi) + precession))
          return minor_rpt
docs: Calculates the number of residues per turn of the minor helix.
  
          Parameters
          ----------
          minor_repeat : float, optional
              Hydrophobic repeat of the minor helix.
  
          Returns
          -------
          minor_rpt : float
              Residues per turn of the minor helix.