gen_tyvar_sigma : hol_type list -> (hol_type,hol_type) Lib.subst
> gen_tyvar_sigma [“:'c”, “:'a”, “:'bob”]; val it = [{redex = “:γ”, residue = “:%%gen_tyvar%%30”}, {redex = “:α”, residue = “:%%gen_tyvar%%31”}, {redex = “:'bob”, residue = “:%%gen_tyvar%%32”}]: (hol_type, hol_type) Lib.subst