import std/macros
macro items*(t: tuple): untyped =
  result = newNimNode nnkBracket
  if t.len != 0:
    for i in t:
      result.add i
  else:
    let nElem = t.getTypeImpl.len
    if nElem == 0:
      return parseExpr(
        "items(array[0, int]([]))"
      ) # any type shall be ok
    for i in 0..<nElem:
      result.add nnkBracketExpr.newTree(t, newLit i)
  result = newCall(ident"items", result)

type
  Iterable*[T] = concept self  ## Mimic Pythons Iterable. But not checks `iter`
    for i in self: i is T

proc foo[T](it: Iterable[T]) =
  for i in it: echo i

foo (1, 2)