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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 update_pypsa_bus_timeseries(network, timesteps=None):
 """ Updates buses voltage time series in pypsa representation. This function overwrites v_mag_pu_set of buses_t attribute of pypsa network. Be aware that if you call this function with `timesteps` and thus overwrite current time steps it may lead to inconsistencies in the pypsa network since only bus time series are updated but none of the other time series or the snapshots attribute of the pypsa network. Use the function :func:`update_pypsa_timeseries` to change the time steps you want to analyse in the power flow analysis. Parameters network : Network The eDisGo grid topology model overall container timesteps : :pandas:`pandas.DatetimeIndex<datetimeindex>` or :pandas:`pandas.Timestamp<timestamp>` Timesteps specifies which time steps of the time series to export to pypsa representation. If None all time steps currently existing in pypsa representation are updated. If not None current time steps are overwritten by given time steps. Default: None. """

    if timesteps is None:
        timesteps = network.pypsa.buses_t.v_mag_pu_set.index
    # check if timesteps is array-like, otherwise convert to list
    if not hasattr(timesteps, "__len__"):
        timesteps = [timesteps]
    buses = network.pypsa.buses.index
    v_mag_pu_set = _pypsa_bus_timeseries(network, buses, timesteps)
    network.pypsa.buses_t.v_mag_pu_set = v_mag_pu_set