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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_metadata(self):
 """ List all scenario metadata indicators available in the connected data source """

        url = self.base_url + 'metadata/types'
        headers = {'Authorization': 'Bearer {}'.format(self.auth())}
        r = requests.get(url, headers=headers)
        return pd.read_json(r.content, orient='records')['name']