pycharm中输入 __metaclass__=type 会提示 unresolved reference 错误，怎么解决？
python新手学习中

__metaclass__ ＝ type
class Rectangle:
    def __init__(self):
        self.width=0
        self.height=0
    def __setSize__(self,size):
        self.width, self.height=size
    def __getSize__(self):
        return self.width,self.height
    size=property(getSize,setSize)

问题已解决。代码如下。
class Rectangle:
    def __init__(self):
        self.width = 0
        self.height = 0

    def setsize(self, size):
        self.width, self.height = size

    def getsize(self):
        return self.width, self.height
    size = property(getsize, setsize)