decl flow_control_test : Unit -> Unit
def flow_control_test = {
//   if && || a < b
//         || a == b
//      && b < c
//      && c > 10

  if ((a < b) || (a == b)) && (b < c)
  then IO.print x
  elif x < 0
  then {
    ; ++x
    ; IO.print y
  } else {
    return {}
  }

  while (a > 0) && (!array.is_empty)
  do {
    ; --a
    ; array.pop
  }

  while x < 10 do
    x += x + 3

  for i in 0..y do {
    ; IO.print i
  }

  for & i & j
  in (& 0..y & 0..k)
  do { // TODO: decide ??? does it work (like auto zip) ???
    ; IO.print 1
    ; IO.print 2
    ; IO.print 128
  }

  loop {
    ; ++y
    if y > 100 then
      break
  }
}