   # the trick.
   Parenthetical: [
     o "( Line )",                               -> new ParentheticalNode $2
-  ]
-
-  # A language extension to CoffeeScript from the outside. We simply pass
-  # it through unaltered.
-  Extension: [
-    o "EXTENSION",                              -> yytext
   ]
 
   # The condition portion of a while loop.

  # A single parameter in a function definition can be ordinary, or a splat
  # that hoovers up the remaining arguments.
  Param: [
    o "PARAM",                                  -> new LiteralNode yytext
    o "Param . . .",                            -> new SplatNode $1
  ]

  # A splat that occurs outside of a parameter list.

  # (optional) reference to the current index. Or, *key, value*, in the case
  # of object comprehensions.
  ForVariables: [
    o "IDENTIFIER",                             -> [$1]
    o "IDENTIFIER , IDENTIFIER",                -> [$1, $3]
  ]

  # The source of a comprehension is an array or object with an optional filter
