anchor.diff:          !     density_matrices = true/false,
           !     density_matrix_file = filename,
           !     even_selection = true/false,
  +	!     multiref = true/false,
  +	!     second_ref =second reference,
           ! }
   
           ! In/Out:
  
positive.code:         type(ccmc_in_t), intent(out) :: ccmc_in
  
          integer :: ccmc_table, err
          character(28), parameter :: keys(8) = [character(28) :: 'move_frequency', 'cluster_multispawn_threshold', &
                                                                  'full_non_composite', 'linked', 'vary_shift_reference', &
                                                                  'density_matrices', 'density_matrix_file', 'even_selection']
  
          if (aot_exists(lua_state, opts, 'ccmc')) then
  
  
negative.code:             call aot_get_val(ccmc_in%density_matrices, err, lua_state, ccmc_table, 'density_matrices')
              call aot_get_val(ccmc_in%density_matrix_file, err, lua_state, ccmc_table, 'density_matrix_file')
              call aot_get_val(ccmc_in%even_selection, err, lua_state, ccmc_table, 'even_selection')
              call aot_get_val(ccmc_in%multiref, err, lua_state, ccmc_table, 'multiref')
              call aot_get_val(ccmc_in%second_ref, err, lua_state, ccmc_table, 'second_ref')
  
              call warn_unused_args(lua_state, keys, ccmc_table)
  
  