α : Type u_1
as bs : List α
⊢ as ++ bs ++ bs = as ++ (bs ++ bs)
rewrite.lean:12:20-12:29: error: tactic 'rewrite' failed, did not find instance of the pattern in the target expression
  List.reverse (List.reverse ?as)
α : Type u_1
as bs : List α
⊢ as ++ [] ++ [] ++ bs ++ bs = as ++ (bs ++ bs)
x y z : Nat
h₁ : x = y
h₂ : y = z
⊢ x = z
rewrite.lean:31:9-31:20: error: tactic 'rewrite' failed, did not find instance of the pattern in the current goal
x y z : Nat
h₁ : 0 + x = y
h₂ : 0 + y = z
⊢ x = z
m n k : Nat
 : n = m
h : k = m
⊢ k = n
rewrite.lean:49:69-50:10: error: unsolved goals
α : Type
p : Prop
a b c : α
h : p → a = b
⊢ b = c

α : Type
p : Prop
a b c : α
h : p → a = b
⊢ p