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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_upload_key(self):
 """Get the `Key` from the S3 bucket for the uploaded file. :returns: Key (object) of the uploaded file. :rtype: :py:class:`boto.s3.key.Key` """


        if not hasattr(self, '_upload_key'):
            self._upload_key = self.get_storage().bucket.get_key(
                self.cleaned_data['key_name'])
        return self._upload_key