code: def raise_415(instance, msg=None):
      
      instance.response.status = 415
      if msg:
          instance.response.body_raw = {'error': msg}
      raise ResponseException(instance.response)
docs: Abort the current request with a 415 (Unsupported Media Type) response
      code. If the message is given it's output as an error message in the
      response body (correctly converted to the requested MIME type).
  
      :param instance: Resource instance (used to access the response)
      :type instance: :class:`webob.resource.Resource`
      :raises: :class:`webob.exceptions.ResponseException` of status 415