code: def bake(self, start_response):
          
          if isinstance(self._content, six.text_type):
              self._content = self._content.encode('utf8')
  
          if self._content_length is None:
              self._content_length = len(self._content)
  
          self._headers[HttpResponseHeaders.CONTENT_LENGTH] = \
              str(self._content_length)
          headers = list(self._headers.items())
          cookies = [(HttpResponseHeaders.SET_COOKIE, v.OutputString())
                     for _, v in self._cookies.items()]
  
          if len(cookies):
              headers = list(headers) + cookies
          start_response(self._status_code, headers)
  
          if isinstance(self._content, six.binary_type):
              return [self._content]
  
          return self._content
docs: Bakes the response and returns the content.
  
          Args:
              start_response (:obj:`callable`): Callback method that accepts
                  status code and a list of tuples (pairs) containing headers'
                  key and value respectively.