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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_metadata(self, href=None, metadata=None, version=None):
 """Update the metadata in a bundle. 'href' the relative href to the metadata. May not be None. 'metadata' may be None, or an object that can be converted to a JSON string. See API documentation for restrictions. The conversion will take place before the API call. 'version' the object version. May be None; if not None, must be an integer, and the version must match the version of the bundle. If not, a 409 conflict error will cause an APIException to be thrown. Returns a data structure equivalent to the JSON returned by the API. If the response status is not 2xx, throws an APIException. If the JSON to python data struct conversion fails, throws an APIDataException."""


        # Argument error checking.
        assert href is not None
        assert metadata is not None
        assert version is None or isinstance(version, int)

        # Prepare the data we're going to include in our bundle update.
        data = None

        fields = {}
        if version is not None:
            fields['version'] = version
        fields['data'] = json.dumps(metadata)

        data = fields

        raw_result = self.put(href, data)

        if raw_result.status < 200 or raw_result.status > 202:
            raise APIException(raw_result.status, raw_result.json)

        # Convert the JSON to a python data struct.

        return self._parse_json(raw_result.json)