(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
ob_clean — Clean (erase) the contents of the active output buffer
   This function calls the output handler
   (with the PHP_OUTPUT_HANDLER_CLEAN flag),
   discards it's return value
   and cleans (erases) the contents of the active output buffer.
  
This function does not turn off the active output buffer like ob_end_clean() or ob_get_clean() does.
   ob_clean() will fail
   without an active output buffer started with the
   PHP_OUTPUT_HANDLER_CLEANABLE flag.
  
This function has no parameters.
   If the function fails it generates an E_NOTICE.