<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def create_metadata(self, **params):
 """ Adds metadata to a media element, such as image descriptions for visually impaired. Docs: https://developer.twitter.com/en/docs/media/upload-media/api-reference/post-media-metadata-create """

        params = json.dumps(params)
        return self.post("https://upload.twitter.com/1.1/media/metadata/create.json", params=params)