 #     (2 + 3) * 4
 operators = [
   ["right",     '?', 'NEW']
+  ["left",      'CALL_START', 'CALL_END']
   ["nonassoc",  '++', '--']
   ["right",     'UNARY']
   ["left",      'MATH']

  Invocation: [
    o "Value OptFuncExist Arguments",           -> new CallNode $1, $3, $2
    o "Invocation OptFuncExist Arguments",      -> new CallNode $1, $3, $2
  ]

  # An optional existence check on a function.

  Arguments: [
    o "CALL_START CALL_END",                    -> []
    o "CALL_START ArgList OptComma CALL_END",   -> $2
  ]

  # A reference to the *this* current object.
