anchor.diff:  
   COMMA
      : 'COMMA'
  -   ;
  -
  -
  -BRANCH
  -   : 'BRANCH'
      ;
   
   
  
positive.code:    ;
  
  branch
     : LITERAL_BRANCH BRANCH SEMI
     ;
  
  access
  
negative.code: 
  
  REVISION
     : INT ( '.' INT )*
     ;
  
  
  
  STRING
    : '@' (~[@] | '@@')* '@';
  
  
  SEMI
  