class Set:
    def __init__(self,value=):
        self.data=
        self.concat(value)
    def intersect(self,other):
        res=
        for x in self.data:
            if x in other:
                res.append(x)
        return Set(res)
    def union(self,other):
        res=self.data
        for x in other:
            if not x in res:
                res.append(x)
        return Set(res)
    def concat(self,value):
        for x in value:
            if not x in self.data:
                self.data.append(x)
    def __len__(self):
        return len(self.data)
    def __getitem__(self,key):
        return self.data
    def __and__(self,other):
        return self.intersect(other)
    def __or__(self,other):
        return self.union(other)
    def __repr__(self):
        return 'Set:'+repr(self.data)
X=Set()
print(X.union(Set()))
print(X | Set())

print(X.union(Set()))
print(X | Set())

class Set:
    def __init__(self,value=[]):
        self.data=[]
        self.concat(value)
    def intersect(self,other):
        res=[]
        for x in self.data:
            if x in other:
                res.append(x)
        return Set(res)
    def union(self,other):
        res=self.data
        for x in other:
            if not x in res:
                res.append(x)
        return Set(res)
    def concat(self,value):
        for x in value:
            if not x in self.data:
                self.data.append(x)
    def __len__(self):
        return len(self.data)
    def __getitem__(self,key):
        return self.data
    def __and__(self,other):
        return self.intersect(other)
    def __or__(self,other):
        return self.union(other)
    def __repr__(self):
        return 'Set:'+repr(self.data)
X=Set([1,3,5,7])
print(X.union([1,4,7]))
print(X | [1,4,6])

>>> import _thread
>>> _thread
<module '_thread' (built-in)>

_original_start_new_thread = thread.start_new_thread

print(thread)

X=Set([1,3,5,7])
print(X.union(Set([1,4,7])))
print(X | Set([1,4,6]))