code: def create_session(self, **params):
          
  
          required_keys = ('market', 'currency', 'locale', 'pickupplace',
                           'dropoffplace', 'pickupdatetime', 'dropoffdatetime',
                           'driverage')
  
          service_url = "{url}/{params_path}".format(
              url=self.PRICING_SESSION_URL,
              params_path=self._construct_params(params, required_keys)
          )
  
          poll_path = self.make_request(service_url,
                                        headers=self._session_headers(),
                                        callback=lambda resp: resp.headers[
                                            'location'],
                                        userip=params['userip'])
  
          return "{url}{path}".format(url=self.API_HOST, path=poll_path)
docs: Create the session
          date format: YYYY-MM-DDThh:mm
          location: ISO code