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