带有参数并更改类型的Python装饰器类

def returns(object):
    \"\"\"Enforces return to a specific type\"\"\"
    def __init__(self, returns):
        self.returns = returns

    def __call__(self, func):
        def wrapped(*args):
            out = func(*args)
            return self.returns(out)
        return wrapped

@returns(int) 
def test():
    return \'4\'

------------------------------------------------------------
Traceback (most recent call last):
  File \"\", line 1, in <module>
  File \"\", line 122, in runfile
    execfile(filename, glbs)
  File \"\", line 33, in <module>
    @returns(int)
TypeError: \'NoneType\' object is not callable