gets the dialog between user_1 and user_2
    :param user_1: the first user in dialog (owner or opponent)
    :param user_2: the second user in dialog (owner or opponent)
    :return: queryset which include dialog between user_1 and user_2 (queryset can be empty)

def get_dialogs_with_user(user_1, user_2):
    """
    gets the dialog between user_1 and user_2
    :param user_1: the first user in dialog (owner or opponent)
    :param user_2: the second user in dialog (owner or opponent)
    :return: queryset which include dialog between user_1 and user_2 (queryset can be empty)
    """
    return Dialog.objects.filter(
        Q(owner=user_1, opponent=user_2) | Q(opponent=user_1, owner=user_2))