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