case intro
n : Nat
m : Nat := n
h : ∃ (k : Nat), id k = m
a : Nat
e : id a = m
⊢ 0 + n = n
case intro
a : Nat
m : Nat := id a
h : ∃ (k : Nat), id k = m
⊢ 0 + id a = id a
case intro
n : Nat
m : Nat := n
h : ∃ (k : Nat), m = id k
a : Nat
e : m = id a
⊢ 0 + n = n
case intro
n : Nat
m : Nat := n
h : ∃ (k : Nat), m = id k
⊢ 0 + n = n
substlet.lean:25:2-25:9: error: tactic 'subst' failed, variable 'v' is a let-declaration
n : Nat
h : n = 0
m : Nat := n + 1
v : Nat := m + 1
this : v = n + 2
⊢ 0 + n = 0