anchor.diff:  options {
   tokenVocab=Sparql; // reuse token types
   ASTLabelType=CommonTree; // $label will have type CommonTree
  -//output=template;
  +output=AST; //template;
   }
   
   @header {
  
positive.code: 	
  triplesNode
      : ^(COLLECTION graphNode+)
      | ^(TRIPLE objectList)
      ;
  
  graphNode
  
negative.code:     ;
  
  varOrTerm
      : var | graphTerm | BLANK_NODE
      ;
  
  varOrIRIref
  