proposition: Lemma example: (1 + 0 + 1) * (1 + 1) = (1 + 1) + (1 + 1).
proof: Proof. apply do_quote. Admitted. End approach_B. End simple. Module with_vars. Lemma sum_assoc {A B C}: (A+B)+C → A+(B+C). intuition. Defined.
imports: Coq.Classes.Morphisms Coq.Program.Program Coq.Unicode.Utf8