code: def chi_p_from_spherical(mass1, mass2, spin1_a, spin1_azimuthal, spin1_polar,
                           spin2_a, spin2_azimuthal, spin2_polar):
      
      spin1x, spin1y, _ = _spherical_to_cartesian(
          spin1_a, spin1_azimuthal, spin1_polar)
      spin2x, spin2y, _ = _spherical_to_cartesian(
          spin2_a, spin2_azimuthal, spin2_polar)
      return chi_p(mass1, mass2, spin1x, spin1y, spin2x, spin2y)
docs: Returns the effective precession spin using spins in spherical
      coordinates.