k : ℕ
⊢ [Fin.cons (0, 0).fst 0] = [0]
k : ℕ
⊢ antidiagonalTuple (k + 1) 0 = [0]
rw [antidiagonalTuple, antidiagonal_zero, List.bind_singleton, antidiagonalTuple_zero_right k,
  List.map_singleton]
no goals
k : ℕ
⊢ [Fin.cons (0, 0).fst 0] = [0]
exact congr_arg (fun x => [x]) Matrix.cons_zero_zero