<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def load_clients(stream, configuration_class=ClientConfiguration):
 """ Loads client configurations from a YAML document stream. :param stream: YAML stream. :type stream: file :param configuration_class: Class of the configuration object to create. :type configuration_class: class :return: A dictionary of client configuration objects. :rtype: dict[unicode | str, dockermap.map.config.client.ClientConfiguration] """

    client_dict = yaml.safe_load(stream)
    if isinstance(client_dict, dict):
        return {client_name: configuration_class(**client_config)
                for client_name, client_config in six.iteritems(client_dict)}
    raise ValueError("Valid configuration could not be decoded.")