'Get a required request parameter.
Args:
param_name: name of request parameter to fetch.
Returns:
parameter value
Raises:
NotEnoughArgumentsError: if parameter is not specified.'

def _get_required_param(self, param_name):

    value = self.request.get(param_name)
    if (not value):
        raise NotEnoughArgumentsError((param_name + '    not    specified'))
    return value
