Source

File: wp-admin/includes/class-wp-screen.php

public function render_screen_reader_content( $key = '', $tag = 'h2' ) {

		if ( ! isset( $this->_screen_reader_content[ $key ] ) ) {
			return;
		}
		echo "<$tag class='screen-reader-text'>" . $this->_screen_reader_content[ $key ] . "</$tag>";
	}