To prove closure of this and the context free value language which is under homomorphism, so let's start with a parameter G for a language L and let H be the homomorphism of the terminal symbols of G. And H has a grammar which we can construct by replacing each terminal A in the body of any production of G by the string H of A. So for example here is, G is our customary grammar for G to the N one to the N. And here is our. 