function command( pres ) {
	return onCommand;

	/**
	* Prints a "blank" slide.
	*
	* @private
	*/
	function onCommand() {
		var str = repeat( pres._opts.newline, pres.height+1 );
		pres._repl._ostream.write( str );
		pres._repl.once( 'drain', onDrain );

		/**
		* Callback invoked upon a `drain` event.
		*
		* @private
		*/
		function onDrain() {
			/*
			* [ANSI escape sequences][1]:
			*
			* -   `\u001b`: ESC, the escape character
			* -   `[1T`: scroll down one line
			* -   `[1G`: move the cursor to the beginning of the line
			*
			* [1]: https://en.wikipedia.org/wiki/ANSI_escape_code
			*/
			var str = '\u001b[1T\u001b[1G';
			pres._repl._ostream.write( str );
		}
	}
}
Returns a callback to be invoked upon calling the `blank` command.

@private
@param {Presentation} pres - presentation instance
@returns {Function} callback