docs: def _vector_coef_op_right(func):
          """decorator for operator overloading when VectorCoefs is on the
          right"""
          @wraps(func)
          def verif(self, vcoef):
              if isinstance(vcoef, numbers.Number):
                  return VectorCoefs(func(self, self.scoef1._vec, vcoef),
                                     func(self, self.scoef2._vec, vcoef),
                                     self.nmax, self.mmax)
              else:
                  raise TypeError(err_msg['no_combi_VC'])
          return verif