docs: def _submit_batch(self, url, batch):
          """Submit the batch, returning the JSON->dict from the last HTTP response"""
          # TODO: validate column_name
          batch_parts = batch.parts()
  
          guid = ""
          headers = {
              'User-Agent': 'kentik-python-api/0.1',
              'Content-Type': 'application/json',
              'X-CH-Auth-Email': self.api_email,
              'X-CH-Auth-API-Token': self.api_token
          }
  
          # submit each part
          last_part = dict()
          for batch_part in batch_parts:
              # submit
              resp = requests.post(url, headers=headers, data=batch_part.build_json(guid))
  
              # print the HTTP response to help debug
              print(resp.text)
  
              # break out at first sign of trouble
              resp.raise_for_status()
              last_part = resp.json()
              guid = last_part['guid']
              if guid is None or len(guid) == 0:
                  raise RuntimeError('guid not found in batch response')
  
          return last_part