code: def product_ops(self, indices, conjugate):
          
          pterm = PauliTerm('I', 0, 1.0)
          for conj, index in zip(conjugate, indices):
              pterm = pterm * self._operator_generator(index, conj)
  
          pterm = pterm.simplify()
          return pterm
docs: Convert a list of site indices and coefficients to a Pauli Operators
          list with the Jordan-Wigner (JW) transformation
  
          :param List indices: list of ints specifying the site the fermionic operator acts on,
                               e.g. [0,2,4,6]
          :param List conjugate: List of -1, 1 specifying which of the indices are
                                 creation operators (-1) and which are annihilation
                                 operators (1).  e.g. [-1,-1,1,1]