code: def create_file_chunk_url(self, upload_id, chunk_num, chunk):
          
          chunk_len = len(chunk)
          hash_data = HashData.create_from_chunk(chunk)
          one_based_index = chunk_num + 1
  
          def func():
              return self.data_service.create_upload_url(upload_id, one_based_index, chunk_len,
                                                         hash_data.value, hash_data.alg)
  
          resp = retry_until_resource_is_consistent(func, self.waiting_monitor)
          return resp.json()
docs: Create a url for uploading a particular chunk to the datastore.
          :param upload_id: str: uuid of the upload this chunk is for
          :param chunk_num: int: where in the file does this chunk go (0-based index)
          :param chunk: bytes: data we are going to upload
          :return: