A decorator that converts the request body into a function parameter based on the specified schema.

        :param param_name: The parameter which receives the argument.
        :param schema: The schema class or instance used to deserialize the request body toa Python object.
        :return: A function

def from_body(self, param_name, schema):
        """
        A decorator that converts the request body into a function parameter based on the specified schema.

        :param param_name: The parameter which receives the argument.
        :param schema: The schema class or instance used to deserialize the request body toa Python object.
        :return: A function
        """

        schema = schema() if isclass(schema) else schema

        def decorator(func):
            @functools.wraps(func)
            def wrapper(*args, **kwargs):
                kwargs[param_name] = self.__parse_body(schema)
                return func(*args, **kwargs)
            return wrapper
        return decorator