docs: 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))