function command( repl ) {
	return onCommand;

	/**
	* Gets (and sets) REPL settings.
	*
	* @private
	* @param {string} [name] - setting name
	* @param {*} [value] - new setting value
	* @returns {(void|*)} setting value or undefined
	*/
	function onCommand() {
		var nargs;
		var v;

		nargs = arguments.length;
		if ( nargs === 0 ) {
			repl._ostream.write( help( repl._settings ) );
			return;
		}
		if ( nargs === 1 ) {
			try {
				v = repl.settings( arguments[ 0 ] );
			} catch ( err ) {
				debug( 'Error: %s', err.message );
				repl._ostream.write( format( 'Error: %s\n', err.message ) );
				return;
			}
			return v;
		}
		try {
			repl.settings( arguments[ 0 ], arguments[ 1 ] );
		} catch ( err ) {
			debug( 'Error: %s', err.message );
			repl._ostream.write( format( 'Error: %s\n', err.message ) );
			return;
		}
		log( repl, '\nSuccessfully updated setting.' );
	}
}
Returns a callback to be invoked upon calling the `settings` command.

@private
@param {REPL} repl - REPL instance
@returns {Function} callback