code: def chi_eff_from_spherical(mass1, mass2, spin1_a, spin1_polar,
                             spin2_a, spin2_polar):
      
      spin1z = spin1_a * numpy.cos(spin1_polar)
      spin2z = spin2_a * numpy.cos(spin2_polar)
      return chi_eff(mass1, mass2, spin1z, spin2z)
docs: Returns the effective spin using spins in spherical coordinates.