def _message_from_pods_dict(errors_dict):
    """Form a message string from a 'pod kind': [pod name...] dict.

    Args:
      - errors_dict: a dict with keys pod kinds as string and values
                     names of pods of that kind
    Returns: a string message
    """
    msg_list = [
        "{0}: {1}".format(key, ", ".join(msg)) for key, msg in errors_dict.items()
    ]
    return "; ".join(msg_list)