python编写一个类，实现添加元素（如果存在则不添加），删除元素，弹出元素（pop）,集合差集运算，集合并集运算，判断两个集合是否相等，>=运算符重载（集合包含关系），支持内置函数len，清空集合所有元素。

下面是一个简单的示例代码：

class MySet:
    def __init__(self):
        self.elements = []

    def add(self, element):
        if element not in self.elements:
            self.elements.append(element)

    def remove(self, element):
        if element in self.elements:
            self.elements.remove(element)

    def pop(self):
        if len(self.elements) > 0:
            return self.elements.pop()

    def difference(self, other_set):
        result_set = MySet()
        for element in self.elements:
            if element not in other_set.elements:
                result_set.add(element)
        return result_set

    def union(self, other_set):
        result_set = MySet()
        for element in self.elements:
            result_set.add(element)
        for element in other_set.elements:
            result_set.add(element)
        return result_set

    def __eq__(self, other_set):
        if len(self.elements) != len(other_set.elements):
            return False
        for element in self.elements:
            if element not in other_set.elements:
                return False
        return True

    def __ge__(self, other_set):
        for element in other_set.elements:
            if element not in self.elements:
                return False
        return True

    def __len__(self):
        return len(self.elements)

    def clear(self):
        self.elements = []

可以用以下方式测试：

# 创建两个集合
set1 = MySet()
set2 = MySet()

# 添加元素
set1.add(1)
set1.add(2)
set1.add(3)
set2.add(2)
set2.add(3)
set2.add(4)

# 删除元素
set1.remove(2)

# 弹出元素
popped_element = set1.pop()

# 集合差集运算
difference_set = set1.difference(set2)

# 集合并集运算
union_set = set1.union(set2)

# 判断两个集合是否相等
is_equal = set1 == set2

# >=运算符重载（集合包含关系）
is_superset = set1 >= set2

# 支持内置函数len
set_len = len(set1)

# 清空集合所有元素
set1.clear()