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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 _retrieve_metadata(stream, channel_name):
 """Retrieve basic metadata by reading the first file in the cache Parameters stream: lal stream object Stream containing a channel we want to learn about channel_name: str The name of the channel we want to know the dtype and sample rate of Returns ------- channel_type: lal type enum Enum value which indicates the dtype of the channel sample_rate: int The sample rate of the data within this channel """

        lalframe.FrStreamGetVectorLength(channel_name, stream)
        channel_type = lalframe.FrStreamGetTimeSeriesType(channel_name, stream)
        create_series_func = _fr_type_map[channel_type][2]
        get_series_metadata_func = _fr_type_map[channel_type][3]
        series = create_series_func(channel_name, stream.epoch, 0, 0,
                            lal.ADCCountUnit, 0)
        get_series_metadata_func(series, stream)
        return channel_type, int(1.0/series.deltaT)