def ensure_dtraj_list(dtrajs):
    r"""Makes sure that dtrajs is a list of discrete trajectories (array of int)

    """
    if isinstance(dtrajs, list):
        # elements are ints? then wrap into a list
        if is_list_of_int(dtrajs):
            return [np.array(dtrajs, dtype=int)]
        else:
            for i in range(len(dtrajs)):
                dtrajs[i] = ensure_dtraj(dtrajs[i])
            return dtrajs
    else:
        return [ensure_dtraj(dtrajs)]