You are part of a secret organisation that supervises extraterrestrial lifeforms who live on Earth. One of the main contributions of the organisation is that they hide their existence from ordinary humans.

Write a predicate mib(A, B, PreTruth, PostTruth) that is true if PostTruth is the result fo substituting every occurrence of A by B in a term.

?- mib(alien, friend, hug(alien, child), PostTruth).
PostTruth = hug(friend, child)

These links may come in handy:

• functor/3¹
• arg/3²
• Verify Type of a Term³