anchor.diff:      '\'' (~'\'')* '\'' ( '\'' (~'\'')* '\'' )* 
       ;
   
  +
   IntegerLiteral
      : Digit+;
  -
  -
  -HostIdentifier
  -    : ( Letter | Digit ) ( Letter | Digit | DOT | '-' )* ( Letter | Digit )
  -    ;
   
   //
   // syntactic elements
  
positive.code:     : '0'..'9'
      ;
  
  // syntactic Elements
  Identifier
      : Letter ( Letter | Digit | '_')*
      ;
  
  // literals
  
negative.code: 
  columnOrSuperColumn: StringLiteral;
  
  host: id+=Identifier (id+=DOT id+=Identifier)* -> ^(NODE_ID_LIST $id+);
  
  ipaddr: id+=IntegerLiteral id+=DOT id+=IntegerLiteral id+=DOT id+=IntegerLiteral id+=DOT id+=IntegerLiteral -> ^(NODE_ID_LIST $id+);
  
  port: IntegerLiteral;
  
  