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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 available_features(rtdc_ds):
 """Determine available features for an RT-DC dataset Parameters rtdc_ds: instance of RTDCBase The dataset to check availability for Returns ------- features: dict Dictionary with feature names as keys and instances of `AncillaryFeature` as values. """

        cols = {}
        for inst in AncillaryFeature.features:
            if inst.is_available(rtdc_ds):
                cols[inst.feature_name] = inst
        return cols