anchor.diff:  @ECHO OFF
  +
  +REM change current directory to the location of this script
  +pushd %~dp0
   
   REM create bin directory if it doesn't exist
   if not exist ..\bin mkdir ..\bin
  
positive.code: javac  ..\src\seedu\addressbook\Addressbook.java -d ..\bin
  IF ERRORLEVEL 1 (
      echo ********** BUILD FAILURE ********** 
      exit /b 1
  )
  REM no error here, errorlevel == 0
  
negative.code: 
  REM compare the output to the expected output
  FC actual.txt expected.txt
  
  REM return to previous directory
  popd
  