function command( repl ) {
	return onCommand;

	/**
	* Returns a syntax highlighting color theme.
	*
	* @private
	* @param {string} [name] - theme name
	* @returns {(Object|void)} theme object
	*/
	function onCommand() {
		var theme;
		var name;

		// If no theme name given, get the current theme...
		if ( arguments.length === 0 ) {
			name = repl.settings( 'theme' );
		} else {
			name = arguments[ 0 ];
		}
		try {
			theme = repl.getTheme( name );
		} catch ( err ) {
			repl._ostream.write( format( 'Error: %s\n', err.message ) );
			return;
		}
		return theme;
	}
}
Returns a callback to be invoked upon calling the `getTheme` command.

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