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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 request_all_data(cls, time, pressure=None, **kwargs):
 """Retrieve upper air observations from Iowa State's archive for all stations. Parameters time : datetime The date and time of the desired observation. pressure : float, optional The mandatory pressure level at which to request data (in hPa). If none is given, all the available data in the profiles is returned. kwargs Arbitrary keyword arguments to use to initialize source Returns ------- :class:`pandas.DataFrame` containing the data """

        endpoint = cls()
        df = endpoint._get_data(time, None, pressure, **kwargs)
        return df