Source

File: wp-includes/pomo/mo.php

function export() {
			$tmp_fh = fopen( 'php://temp', 'r+' );
			if ( ! $tmp_fh ) {
				return false;
			}
			$this->export_to_file_handle( $tmp_fh );
			rewind( $tmp_fh );
			return stream_get_contents( $tmp_fh );
		}