anchor.diff:                                | sliceExpression             
                                 | primeExpression             
                                 | nameExpression              
  -                              {
  -                                  t.append( getText( $nameExpression.text ) );
  -                              }
                                 | literalExpression           
  -                              {
  -                                  t.append( getText( $literalExpression.text ) );
  -                              }
                                 ;
   
   binaryExpression
  
positive.code: 
  
  expression
  returns [StringBuilder text]
  @init {
      StringBuilder t = new StringBuilder();
  }
  @after {
      $text = t;
  }
                                : binaryExpression            
                                | unaryExpression             
                                | rangeExpression             
  
negative.code:                               ;
  
  nameExpression
                                : ^( NAME
                                     identifier
                                   )                                
                                | ^( NAME
                                     domainReference
                                     identifier
  