anchor.diff:  	| /* empty */
   ;
   
  +/* https://heycam.github.io/webidl/#idl-extended-attributes
  +   "The ExtendedAttribute grammar symbol matches nearly any sequence of tokens,
  +   however the extended attributes defined in this document only accept a more
  +   restricted syntax."
  +   I use the more restrictive syntax here because it will be more useful for
  +   parsing things in the real world.
  +*/
  +extendedAttribute
  +    : extendedAttributeNoArgs
  +    | extendedAttributeArgList
  +    | extendedAttributeNamedArgList
  +    | extendedAttributeIdent
  +    | extendedAttributeIdentList
  +;
  +
  +/*
  +Here is the extendedAttribute grammar as defined in the spec
  +(https://heycam.github.io/webidl/#prod-ExtendedAttribute):
  +
   extendedAttribute
   	: '(' extendedAttributeInner ')' extendedAttributeRest
   	| '[' extendedAttributeInner ']' extendedAttributeRest
  
positive.code: 	| '[' extendedAttributeInner ']' extendedAttributeInner
  	| '{' extendedAttributeInner '}' extendedAttributeInner
  	| otherOrComma extendedAttributeInner
  	| /* empty */
  ;
  
  other
  	: INTEGER_WEBIDL
  
negative.code: 
  extendedAttributeRest
  	: extendedAttribute
  	| // empty
  ;
  
  extendedAttributeInner
  