call' :: Symbol -> [Operand] -> CodeGen (Maybe Operand)
call' f xs = do
  let name = (Name (T.unpack f))
  global <- findGlobal name
  case global of
    Nothing -> pure Nothing
    Just g -> Just <$> call g xs
call' :: Symbol -> [Operand] -> CodeGen (Maybe Operand)
call' f xs = do
  let name = (Name (T.unpack f))
  global <- findGlobal name
  case global of
    Nothing -> pure Nothing
    Just g -> Just <$> call g xs
call' f xs = do
  let name = (Name (T.unpack f))
  global <- findGlobal name
  case global of
    Nothing -> pure Nothing
    Just g -> Just <$> call g xs