anchor.diff:          !    sys: system being studied (contains required basis information).
           !    f(tot_string_len): bit string representation of the Slater
           !        determinant.
  +        !    excit_gen_data (optional): information for excitation generators.
           ! Out:
           !    d: det_info_t variable.  The following components are set:
           !        occ_list: integer list of occupied spin-orbitals in the
  
positive.code:         ! We return the lists for alpha and beta electrons separately.
          !
          ! In:
          !    f(tot_string_len): bit string representation of the Slater
          !        determinant.
          ! Out:
          !    d: det_info_t variable.  The following components are set:
          !        occ_list: integer list of occupied spin-orbitals in the
  
negative.code:         ! Also return the weights to select i in a double excitation.
          !
          ! In:
          !    sys: system being studied (contains required basis information).
          !    f(tot_string_len): bit string representation of the Slater
          !        determinant.
          !    excit_gen_data (optional): information for excitation generators.
          ! Out:
          !    d: det_info_t variable.  The following components are set:
          !        occ_list: integer list of occupied spin-orbitals in the
  