src/Post.php
public function add_meta( $meta_key = '', $values = '', $unique = false ) {
		return \add_post_meta( $this->id(), $meta_key, $values, $unique );
	}
public function add_meta( $meta_key = '', $values = '', $unique = false ) {
		return \add_post_meta( $this->id(), $meta_key, $values, $unique );
	}
public function add_meta ( $ meta_key = '' , $ values = '' , $ unique = false ) { return \ add_post_meta ( $ this -> id ( ) , $ meta_key , $ values , $ unique ) ; }
Adds Post Meta.

@param string       $meta_key
@param string       $values
@param boolean|bool $unique

@return bool|int
Adds Post Meta .