anchor.diff:  expression
   	: primary ('='^ expression)?
   	;
  -	
  +
   primary
   	:	'('! expression ')'!
   	| (VariableIdentifier|TypeIdentifier|literal) ('.'^ (VariableIdentifier|TypeIdentifier) arguments?)*
   	;
  -	
  +
   arguments
   	:	'(' expressionList? ')'
   	-> ^(ARGS expressionList?)
  
positive.code: }
  
  @rulecatch {
    catch (RecognitionException e) { 
      reportError(e);
      throw e;
    }
  
negative.code: 
  methodDeclaration
  	: methodSignature block
  	-> ^(METHOD methodSignature block?)
  	;
  
  namespace
  