Translates the whole dialog (list of lists) to a string
    :param dialog:
    :return:

def dialog_turns_to_string(dialog):
    """
    Translates the whole dialog (list of lists) to a string
    :param dialog:
    :return:
    """
    # join utterances
    turns_as_strings = map(singe_user_utterances_to_string, dialog)
    # join turns
    return "".join(map(lambda x: x + " " + end_of_turn_symbol + " ", turns_as_strings))