anchor.diff:      ;
   
   brackettedExpression
  -    : OPEN_BRACE expression CLOSE_BRACE -> expression
  +    : OPEN_BRACE expression CLOSE_BRACE -> ^(BRACKETTED_EXPRESSION expression)
       ;
   
   builtInCall
  
positive.code:     ;
  
  unaryExpression
      : op=NEGATION primaryExpression -> ^(UNARY_NOT[$op] primaryExpression)
      | op=PLUS primaryExpression -> ^(UNARY_PLUS[$op] primaryExpression)
      | op=MINUS primaryExpression -> ^(UNARY_MINUS[$op] primaryExpression)
      | primaryExpression -> ^(UNARY primaryExpression)
      ;
  
  
negative.code: PATH_SEQUENCE;
  PATH_PRIMARY;
  PATH_NEGATED;
  BRACKETTED_EXPRESSION;
  UNARY_NOT;
  UNARY_PLUS;
  UNARY_MINUS;
  