WP count children of parent page

This function with shortcode let us to echo number of children of a parent page and with an icon.

function parent_page( $atts ) {
	$a = shortcode_atts( array(
		'parent_id' => 'enter parent ID.',
		'icon_name' => 'enter the icond name.',
	), $atts );
	
	$parent_id = "{$a['parent_id']}";
	$icon_name = "{$a['icon_name']}";
	
	if ( 'publish' === get_post_status( $parent_id )){
		$image = get_template_directory().'/logos/'.$icon_name.'.png';
	
		if(file_exists($image)){
			$returnAll = "<a class='class_".$icon_name."' href='". get_page_link($parent_id). "'>" ; 
			$returnAll .=  get_the_title($parent_id);
			$returnAll .=  "<img src='". get_template_directory_uri(). "/logos/".$icon_name.".png' >";
			$returnAll .=  " <span class='child_count'> ( ". count (get_pages( array('child_of' => $parent_id,)))." )</span>";
			$returnAll .= "</a>";   
		
		}else{
			$returnAll = "The icon not exist!";	
		}
	}else{
		$returnAll = "The page not exist or not published!";	
	} 
	
	return $returnAll;
}
add_shortcode( 'parent_page', 'parent_page' );

Call the function

<?php echo do_shortcode('[parent_page parent_id="15" icon_name="css"]');?>