如何删除前缀的空白wordpress插件行

Good day. I am pulling my hair out with this probably silly problem. i have started writing a new plugin ( wordpress ) . all i have written is the following

 <?php 
 /*
 Plugin Name: Undercon Page Pro
 Plugin URI:#
 Description: Responsive Fullscreen Underconstruction page.
 Version: 0.1
 Author: Nyasha Dhliwayo
 Author URI: #
 License: GPLv2 / Commercial
 */

 //First things first, in the event of direct entry attempt

 // Version 


 $custom_registered_post_returned = "'saver','book'";
 echo $custom_registered_post_returned ;
 exit;

When i run the code just to see if it will echo the strings correctly i find that if i open view page source it has somehow created an extra line of whitespace before the actual string comes out. I have tried using wp_strip_all_tags function but it does not work. Does anyone know how to remove this whitespace. Please help