Source

File: wp-includes/pomo/mo.php

function export_to_file( $filename ) {
			$fh = fopen( $filename, 'wb' );
			if ( ! $fh ) {
				return false;
			}
			$res = $this->export_to_file_handle( $fh );
			fclose( $fh );
			return $res;
		}