decl flow-control-test : -> \unit
def flow-control-test = {
  if && ( || a < b
          || a == b )
     && b < c
  then \io..print: x
  elif x < 0
  then {
    ; x += 1
    ; \io..print: y
  } else {
    return {}
  }

  while && a > 0
        && not: (array..is-empty:)
  do {
    ; a -= 1
    ; 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 { // ??
    ; \io..print: 1
    ; \io..print: 2
    ; \io..print: 128
  }

  loop {
    ; y += 1
    if y > 100 then
      break
  }
}