anchor.diff:  
       // A compilation unit starts with an optional package definition and
       // possibly some javadoc comments
  -    ( {_parseSection==0}? (invariantConditions)* packageName=packageDefinition )?
  +    ( {_parseSection==0}? (invariantCondition)* packageName=packageDefinition )?
       {
         //Now we just need to check to make sure the destination file is older
         if(!getSymtab().isDestinationOlderThanCurrentFile(packageName)) {
  
positive.code: 	// empty statement
      |	SEMI
        
        //assertion
      |   assertCondition
  	)
      ;
  
  
  
negative.code:     //this should just be methods and constructors,
      //but can't find a better place for it.
      ( prePostField | SEMI )*
      rc:RCURLY
      {
        clearInvariants();
        getSymtab().finishClass(new CodePoint(rc.getLine(), rc.getColumn()));
      }
    ;
  
  prePosts 
  