anchor.diff:  options {
   tokenVocab=Sparql; // reuse token types
   ASTLabelType=CommonTree; // $label will have type CommonTree
  -//output=template;
  +output=AST; //template;
   }
   
   @header {
  
positive.code:     ;
      
  quads
      : triplesTemplate? ( quadsNotTriples triplesTemplate? )*
      ;
      
  quadsNotTriples
  
negative.code:     ;
  
  triplesSameSubject
      : ^(TRIPLE propertyListNotEmpty)
      | ^(TRIPLE triplesNode (propertyListNotEmpty)?)
      ;
      
  propertyListNotEmpty
      : (^(SUBJECT varOrTerm) ^(PREDICATE verb) objectList)+
      ;
  
  objectList
      : (^(OBJECT graphNode))+
      ;
  
  verb
  