def render(self, obj, opt=None):
        """ render a Schema/Parameter

        :param obj Schema/Parameter: the swagger spec object
        :param opt dict: render option
        :return: values that can be passed to Operation.__call__
        :rtype: depends on type of 'obj'
        """
        opt = self.default() if opt == None else opt
        if not isinstance(opt, dict):
            raise ValueError('Not a dict: {0}'.format(opt))

        if isinstance(obj, Parameter):
            if getattr(obj, 'in', None) == 'body':
                return self._generate(obj.schema, opt)
            return self._generate(obj, opt=opt)
        elif isinstance(obj, Schema):
            return self._generate(obj, opt)
        else:
            raise ValueError('Not a Schema/Parameter: {0}'.format(obj))
render a Schema/Parameter

        :param obj Schema/Parameter: the swagger spec object
        :param opt dict: render option
        :return: values that can be passed to Operation.__call__
        :rtype: depends on type of 'obj'