WP_Customize_Selective_Refresh::get_partial( string $id )

Source

File: wp-includes/customize/class-wp-customize-selective-refresh.php

public function get_partial( $id ) {
		if ( isset( $this->partials[ $id ] ) ) {
			return $this->partials[ $id ];
		} else {
			return null;
		}
	}