def copy_traj_attributes(target, origin, start):
    """ Inserts certain attributes of origin into target
    :param target: target trajectory object
    :param origin: origin trajectory object
    :param start: :py:obj:`origin` attributes will be inserted in :py:obj:`target` starting at this index
    :return: target: the md trajectory with the attributes of :py:obj:`origin` inserted
    """

    # The list of copied attributes can be extended here with time
    # Or perhaps ask the mdtraj guys to implement something similar?

    target._xyz[start:start+origin.n_frames] = origin._xyz
    target._unitcell_lengths[start:start+origin.n_frames] = origin._unitcell_lengths
    target._unitcell_angles[start:start+origin.n_frames] = origin._unitcell_angles
    target._time[start:start+origin.n_frames] = origin._time

    return target