body
  foo ()[0] == null
  foo (1(2(3 4 5)))[1][1]
  foo (1 2 3)['test'] == null
  foo !(1 0)[1]
  foo !(1 0)[0]
  foo - - -(1 2 3 4 5)[4]

body
  foo (1 (2 (3 4)))
  foo (1 (2 (3 4)))[0]
  foo (1 (2 (3 4)))[1]
  foo (1 (2 (3 4)))[1][0]
  foo (1 (2 (3 4)))[1][1]
  foo (1 (2 (3 4)))[1][1][0]
  foo (1 (2 (3 4)))[1][1][1]
  foo (1 (2 (3 4)))[1][1][3]

body
  foo (error 'message')[0]
  foo (error 'message')[1]

size(a, b)
  return a b

body
  foo size(5, 10)[0]
  foo size(5, 10)[1]

size(a, b)
  (a b)

body
  foo size(5, 10)[0]
  foo size(5, 10)[1]

size()
  (1 2) (3 4)

body
  foo size()[0]
  foo size()[1]
  foo size()[1][1]

image-size(path)
  w = 100
  h = 200
  return w h

body
  size = image-size('test.png')
  foo size
  foo size[0]
  foo size[1]
  foo length(size)

image-size(path)
  100 200

body
  size = image-size('test.png')
  foo size
  foo size[0]
  foo size[1]
  foo length(size)

size = 100 200

body
  foo size
  foo size[0]
  foo size[1]
  foo length(size)

size = (100 200)

body
  foo size
  foo size[0]
  foo size[1]
  foo length(size)