def _get_required_param(self, param_name):
    """Get a required request parameter.

    Args:
      param_name: name of request parameter to fetch.

    Returns:
      parameter value

    Raises:
      NotEnoughArgumentsError: if parameter is not specified.
    """
    value = self.request.get(param_name)
    if not value:
      raise NotEnoughArgumentsError(param_name + " not specified")
    return value
Get a required request parameter.

    Args:
      param_name: name of request parameter to fetch.

    Returns:
      parameter value

    Raises:
      NotEnoughArgumentsError: if parameter is not specified.
    
mapreduce/handlers.py