def trace_ensembles_for_replica(replica, steps):
    """
    List of which ensemble a given replica was in at each MC step.

    Parameters
    ----------
    replica :
        replica ID
    steps : iterable of :class:`.MCStep`
        input data

    Returns
    -------
    list
        list of ensembles
    """
    return [s.active[replica].ensemble for s in steps]