proposition: Lemma zero_le (a : mynat) : 0 ≤ a.
proof: Proof. exists a. rewrite zero_add. reflexivity. Qed.
imports: Unicode.Utf8 Game.Mynat.Definition Game.Mynat.Add Game.Mynat.Mul Game.Mynat.Le Game.World.Addition Game.World.Multiplication Game.World.Proposition Game.World.AdvancedProposition Game.World.AdvancedAddition Game.World.AdvancedMultiplication