function onCommand( oldName, newName ) {
		try {
			repl.renameTheme( oldName, newName );
		} catch ( err ) {
			repl._ostream.write( format( 'Error: %s\n', err.message ) );
			return;
		}
		log( repl, format( '\nSuccessfully renamed theme from `%s` to `%s`.', oldName, newName ) );
	}
Renames a syntax highlighting color theme.

@private
@param {string} oldName - old theme name
@param {string} newName - new theme name
@returns {void}