anchor.diff:  /* - Interface Types - */
   /* - - - - - - - - - - */
   
  +iTypeStatement
  +	//	name = itype { ... }
  +	:	Identifier EqualsOperator
  +		iTypeDeclaration
  +	;
  +
   iTypeDeclaration
  +	//	itype { ... }
   	:	ITypeKeyword LeftBraceElement
  +		iTypeElement*
   		RightBraceElement
  +	;
  +
  +iTypeElement
  +	//	name ( ... )
  +	:	Identifier LeftParenElement
  +		expressionList?
  +		RightParenElement
   	;
   
   /* - Expressions - */
   /* - - - - - - - - */
  +
  +expressionList
  +	:	expression
  +		(',' expression)*
  +	;
   
   expression
   	//	Literals.
  
positive.code: 
  statement
  	//	Declarations.
  	:	typeDeclaration SemicolonElement
  	|	iTypeDeclaration SemicolonElement
  
  	//	Language elements.
  	|	keywordStatement SemicolonElement
  
negative.code: 	|	LeftArrowElement Identifier
  	;
  
  /* - Blocks  - */
  /* - - - - - - */
  
  block
  	//	{ ... }
  	:	LeftBraceElement
  		statement*
  		RightBraceElement
  	;
  
  /* - Types - */
  /* - - - - - */
  
  typeStatement
  	//	name = type { ... }
  	:	Identifier EqualsOperator
  		typeDeclaration
  	;
  
  typeDeclaration
  	//	type { ... }
  	:	TypeKeyword LeftBraceElement
  		RightBraceElement
  	;
  