add_theme_support( 'post-thumbnails' );
function get_excerpt_by_id($post_id){
$the_post = get_post($post_id); //Gets post ID
$the_excerpt = $the_post->post_content; //Gets post_content to be used as a basis for the excerpt
$excerpt_length = 80; //Sets excerpt length by word count
$the_excerpt = strip_tags(strip_shortcodes($the_excerpt)); //Strips tags and images
$words = explode(' ', $the_excerpt, $excerpt_length + 1);
if(count($words) > $excerpt_length) :
array_pop($words);
array_push($words, '[...]');
$the_excerpt = implode(' ', $words);
endif;
$the_excerpt = '