code: def create(self, name, plan, zone,
                 service_type='mongodb', instance_type='mongodb_sharded', version='2.4.6'):
          
          # Build up request data.
          url = self._url
          request_data = {
              'name': name,
              'service': service_type,
              'plan': plan,
              'type': instance_type,
              'version': version,
              'zone': zone
          }
  
          # Call to create an instance.
          response = requests.post(
              url,
              data=json.dumps(request_data),
              **self._default_request_kwargs
          )
  
          # Log outcome of instance creation request.
          if response.status_code == 200:
              logger.info('Successfully created a new instance with: {}'.format(request_data))
          else:
              logger.info('Failed to create instance with: {}'.format(request_data))
              logger.info('Response: [{0}] {1}'.format(response.status_code, response.content))
  
          data = self._get_response_data(response)
          return self._concrete_instance(data)
docs: Create an ObjectRocket instance.
  
          :param str name: The name to give to the new instance.
          :param int plan: The plan size of the new instance.
          :param str zone: The zone that the new instance is to exist in.
          :param str service_type: The type of service that the new instance is to provide.
          :param str instance_type: The instance type to create.
          :param str version: The version of the service the new instance is to provide.