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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def connected_transformer(network, busids):
 """ Get transformer connected to given buses. Parameters network : :class:`pypsa.Network Overall container of PyPSA busids : list List containing bus-ids. Returns ------- :class:`pandas.DataFrame PyPSA transformer. """


    mask = (network.transformers.bus0.isin(busids))

    return network.transformers[mask]