code: def primary_mass(mass1, mass2):
      
      mass1, mass2, input_is_array = ensurearray(mass1, mass2)
      mp = copy.copy(mass1)
      mask = mass1 < mass2
      mp[mask] = mass2[mask]
      return formatreturn(mp, input_is_array)
docs: Returns the larger of mass1 and mass2 (p = primary).