anchor.diff:  //'..' a higher precedence than '->'
   rangeIntervalEntryExpression
       : additiveExpression
  -      (('..'^ |'->'^) additiveExpression)?
  +      (('..'^ | '->'^) additiveExpression)?
       ;
   
   additiveExpression
  
positive.code:     ;
  
  multiplicativeExpression 
      : unaryExpression
        (('*'^ | '/'^ | '%'^ | '&'^) unaryExpression)*
      ;
  
  unaryExpression 
      : prefixOperator unaryExpression
      -> ^(PREFIX_EXPR prefixOperator unaryExpression)
      | exponentiationExpression
      ;
  
  exponentiationExpression
      : primary ('**'^ primary)?
      ;
  
  prefixOperator
      : '$' | '-' |'++' | '--' | '~'
      ;
  
  selfReference
  
negative.code:     FOR_CONTAINMENT;
      ENUM_LIST;
      SUPERCLASS;
      POSTFIX_EXPR;
      EXISTS_EXPR;
      NONEMPTY_EXPR;
  