<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def tarbell_switch(command, args):
 """ Switch to a project. """

    with ensure_settings(command, args) as settings:
        projects_path = settings.config.get("projects_path")
        if not projects_path:
            show_error("{0} does not exist".format(projects_path))
            sys.exit()
        project = args.get(0)
        args.remove(project)
        project_path = os.path.join(projects_path, project)
        if os.path.isdir(project_path):
            os.chdir(project_path)
            puts("\nSwitching to {0}".format(colored.red(project)))
            tarbell_serve(command, args)
        else:
            show_error("{0} isn't a tarbell project".format(project_path))