5. A 0-structure A is called ultrahomogeneous if any o-isomorphism between two finitely generated substructures extends to an automorphism of the whole structure A, i.e. if B, C are finitely generated substructures of A and h:B C is a o-isomorphism, then there is a o-automorphism h of A with h 2 h. (a) Show that (Q,