Why this code gives notice

Hi,

I want to clean up wordpress theme from all notices but i am getting notice on very simple staff:

if (!function_exists(comment_reply)) {
	function comment_reply() {
		if ( is_singular() ) wp_enqueue_script( 'comment-reply' );
	}
}
add_action('get_header', 'comment_reply');

PHP:

Notice is in first line where function_exists and it says 'comment_reply' is not defined. The purpose adding function_exists is already for to check if that function defined and it is wrong by PHP to give such notice even its purpose of current script.
So please tell me how can i rewrite this code not to get this notice?

Thanks.

 

Seems you've forgotten the apostrophes in function name: 'comment_reply'

 

Hello there is small mistake

Use quotes in function name for which you want to check. without quotes php consider as constant

just add if (!function_exists('comment_reply')) {

}