docs: def create_new_content(self, content_data, callback=None):
          """
          Creates a new piece of Content.
          :param content_data (dict): A dictionary representing the data for the new content. Must have keys:
                                      "type", "title", "space", "body".
          :param callback: OPTIONAL: The callback to execute on the resulting data, before the method returns.
                           Default: None (no callback, raw data returned).
          :return: The JSON data returned from the content endpoint,
                   or the results of the callback. Will raise requests.HTTPError on bad input, potentially.
  
          Example content_data:
              {
                  "type": "page",
                  "title": "Example Content title",
                  "space": {
                      "key": "TST"
                  },
                  "body": {
                      "storage": {
                          "value": "<p>This is a new page</p>",
                          "representation": "storage"
                      }
                  }
              }
          """
          assert isinstance(content_data, dict) and set(content_data.keys()) >= self.NEW_CONTENT_REQUIRED_KEYS
          return self._service_post_request("rest/api/content", data=json.dumps(content_data),
                                            headers={"Content-Type": "application/json"}, callback=callback)