合并列表中与其他集合至少有一个交集的每个集合

Question

我们如何合并列表中与其他集合至少有一个交集的每个集合

例如：

lis = [{1, 2, 3}, {2, 4, 6}, {4, 8, 12}, {13, 14, 15}]

# Must union every set which has at least one intersection
# In this case, lis must be [{1, 2, 3, 4, 6, 8, 12}, {13, 14, 15}]
pass

谢谢