Remark wellFormedTermTermsCorrect2 :
forall n : nat,
(wellFormedTerm n <> 0 -> exists t : Term, codeTerm L codeF t = n) /\
(wellFormedTerms n <> 0 ->
exists m : nat, (exists ts : Terms m, codeTerms L codeF m ts = n)).

Lemma wellFormedTermCorrect2 :
forall n : nat,
wellFormedTerm n <> 0 -> exists t : Term, codeTerm L codeF t = n.