anchor.diff:  
   CREATE		: 'create';
   EMITTER		: 'emitter';
  +CONTROLLER	: 'controller';
   WITH		: 'with';
   UPDATER		: 'updater';
   ACTION		: 'action';
  
positive.code: updaterBody
  	:	block
  	;
  
  block
  	:	LBRACE statement* RBRACE
  
negative.code: 	:	ACTION NormalIdentifier formalParameters updaterBody
  	;
  
  controllerDeclaration
  	:	CONTROLLER NormalIdentifier controllerBody
  
  emitterVarDeclaration
  	:	EMITTER NormalIdentifier SEMI
  	;
  
  controllerStateDeclaration
  	:	NormalIdentifier LPAREN RPAREN controllerStateBody
  	;
  
  controllerStateBody
  	: block
  	;
  
  functionBody
  	:	blockWithReturn
  	;
  