def media_upload(self, media, additional_owners=None):
        """
        Uploads an image to Twitter for later embedding in tweets.

        https://dev.twitter.com/rest/reference/post/media/upload

        :param file media:
            The image file to upload (see the API docs for limitations).

        :param list additional_owners:
            A list of Twitter users that will be able to access the uploaded
            file and embed it in their tweets (maximum 100 users).

        :returns:
            A dict containing information about the file uploaded. (Contains
            the media id needed to embed the image in the ``media_id`` field).
        """
        params = {}
        set_list_param(
            params, 'additional_owners', additional_owners, max_len=100)
        return self._upload_media('media/upload.json', media, params)