expr_fvs (Lit _) fv_cand in_scope acc = emptyFV fv_cand in_scope acc
expr_fvs (Lit _) fv_cand in_scope acc = emptyFV fv_cand in_scope acc
expr_fvs (Lit _) fv_cand in_scope acc = emptyFV fv_cand in_scope acc