Note: 
      The closing tag of a PHP block at the end of a file is optional, 
      and in some cases omitting it is helpful when using include()
      or require(), so unwanted whitespace will
      not occur at the end of files, and you will still be able to add
      headers to the response later. It is also handy if you use output
      buffering, and would not like to see added unwanted whitespace
      at the end of the parts generated by the included files.