()
(() | ())
((), ())
((), (), ())
((), (), (), ())
((), () | ())
((), (), () | ())
(() | ((), ()))
(() | ((), (), ()))
(() | (() | ()))
(() | ((), () | ()))
(() | ((), (), () | ()))
(((), ()) | ((), ()))
((() | ()) | (() | ()))
(a)
(a, b)
(a, b, c)
(a | b)
(a, b | c)
(a, b, c, d)
(a, b, c | d)

# comment 0
# comment 0b
( # comment 1
  # comment 1b
  a # comment 2
    # comment 2b
  , # comment 3
    # comment 3b
  b ## comment 4
    ## comment 4b
  , ## comment 5
    ## comment 5b
  c ## comment 6
    ## comment 6b
  | ## comment 7
    ## comment 7b
  d ## comment 8
    ## comment 8b
  ) ## comment 9
    ## comment 9b
