:param path:
    :type path: basestring
    :param argv:
    :type: argv: list, tuple, or None
    :param environ:
    :type environ: dict
    :param command_class: External search command class to instantiate and execute.
    :type command_class: type
    :return:
    :rtype: None

def execute(path, argv=None, environ=None, command_class=ExternalSearchCommand):
    """
    :param path:
    :type path: basestring
    :param argv:
    :type: argv: list, tuple, or None
    :param environ:
    :type environ: dict
    :param command_class: External search command class to instantiate and execute.
    :type command_class: type
    :return:
    :rtype: None
    """
    assert issubclass(command_class, ExternalSearchCommand)
    command_class(path, argv, environ).execute()