code: def update_item(self, payload, last_modified=None):
          
          to_send = self.check_items([payload])[0]
          if last_modified is None:
              modified = payload["version"]
          else:
              modified = last_modified
          ident = payload["key"]
          headers = {"If-Unmodified-Since-Version": str(modified)}
          headers.update(self.default_headers())
          req = requests.patch(
              url=self.endpoint
              + "/{t}/{u}/items/{id}".format(
                  t=self.library_type, u=self.library_id, id=ident
              ),
              headers=headers,
              data=json.dumps(to_send),
          )
          self.request = req
          try:
              req.raise_for_status()
          except requests.exceptions.HTTPError:
              error_handler(req)
          return True
docs: Update an existing item
          Accepts one argument, a dict containing Item data