Construct a most-general unifier of two term lists.
Construct a most-general unifier of two term lists. If the lists unify with substitution s, return Some (s). Otherwise, return None if the lists of terms cannot be unified.
Construct a most-general unifier of two terms.
Construct a most-general unifier of two terms. If the terms unify with substitution s, return Some (s). Otherwise, return None if the terms cannot be unified.