如何遍历这些集合并显示其中的所有公共数字？

def find_common_numbers(collections):
    common_numbers = set()
    first_collection = collections[0]

    for number in first_collection:
        is_common = True

        for i in range(1, len(collections)):
            if number not in collections[i]:
                is_common = False
                break

        if is_common:
            common_numbers.add(number)

    return common_numbers

# 示例集合
collection1 = [1, 2, 3, 4, 5]
collection2 = [2, 4, 6, 8, 10]
collection3 = [3, 4, 5, 6, 7]

# 调用函数并显示结果
collections = [collection1, collection2, collection3]
common_numbers = find_common_numbers(collections)
print("公共数字：", common_numbers)