count_holes_in_currentDets Function

    function count_holes_in_currentDets() result(holes)
        integer :: holes
        integer(n_int), pointer :: ilut_parent(:)
        integer :: nI_parent(nel), unused_flags, idet
        real(dp) :: parent_sign(lenof_sign)

        holes = 0

        do idet = 1, int(TotWalkers)

            ilut_parent => CurrentDets(:, idet)

            call extract_bit_rep(ilut_parent, nI_parent, parent_sign, unused_flags, idet, &
                                 fcimc_excit_gen_store)

            if (IsUnoccDet(parent_sign)) then
                holes = holes + 1
            end if

        end do

    end function count_holes_in_currentDets