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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 get(feature_name):
 """Returns the MetadataExtractor that can extract information about the provided feature name. Raises: UnsupportedFeature: If no extractor exists for the feature name. """

        implementations = MetadataExtractor._implementations()
        try:
            return implementations[feature_name]
        except KeyError:
            raise UnsupportedFeatureException(
                'no MetadataExtractor registered for feature "{feature_name}" '
                '(try any of the following: {supported_features})'
                .format(feature_name=feature_name,
                        supported_features=', '.join(sorted(implementations))))