public function retrieve_meta_for_field( $field, $post ) {
		$meta = get_post_meta( $post->ID, $field['meta'], ! $field['multiple'] );
		$meta = ! empty( $meta ) ? $meta : $field['std'];
		$meta = ( is_array( $meta ) ) ? self::array_map_deep( 'esc_attr', $meta ) : esc_attr( $meta );
		return $meta;
	}