def f : List Nat → IO Unit :=
fun xs =>
  xs.forM fun x =>
    if (x == 0) = true then do
      IO.println "foo"
      IO.println "zero"
    else
      if (x % 2 == 0) = true then do
        IO.println x
        IO.println "even"
      else do
        IO.println x
        IO.println "odd"
if true = true then 1 else 0 : Nat
if h : true = true then 1 else 0 : Nat