s = parse('1')
expect(to_string(s)).toEqual('1')

s = parse('+1')
expect(to_string(s)).toEqual('(+ 1)')

s = parse('1 + +-1')
expect(to_string(s)).toEqual('(+ 1 (+ (- 1)))')

s = parse('1 + 2 * 3')
expect(to_string(s)).toEqual('(+ 1 (* 2 3))')

s = parse('a + b * c * d + e')
expect(to_string(s)).toEqual('(+ (+ a (* (* b c) d)) e)')

s = parse('f . g . h')
expect(to_string(s)).toEqual('(. f (. g h))')

s = parse('1 + 2 + f . g . h * 3 * 4')
expect(to_string(s)).toEqual('(+ (+ 1 2) (* (* (. f (. g h)) 3) 4))')

s = parse('--1 * 2')
expect(to_string(s)).toEqual('(* (- (- 1)) 2)')

s = parse('--f . g')
expect(to_string(s)).toEqual('(- (- (. f g)))')

s = parse('-9!')
expect(to_string(s)).toEqual('(- (! 9))')

s = parse('f . g !')
expect(to_string(s)).toEqual('(! (. f g))')

s = parse('(((0)))')
expect(to_string(s)).toEqual('0')

s = parse('x[0][1]')
expect(to_string(s)).toEqual('([ ([ x 0) 1)')

s = parse(`
  a ? b :
  c ? d
  : e
`)
expect(to_string(s)).toEqual('(? a b (? c d e))')

s = parse('a = 0 ? b : c = d')
expect(to_string(s)).toEqual('(= a (= (? 0 b c) d))')