我理解这一点没有问题:
a = [1,2,3,4]
b = [x for x in a]
我以为就是这样,但后来我找到了这个片段:
a = [[1,2],[3,4],[5,6]]
b = [x for xs in a for x in xs]
这使得b = [1,2,3,4,5,6].问题是我在理解语法方面遇到了麻烦[x for xs in a for x in xs],有人能解释一下它是如何工作的吗？