python通用的列表解析结构
通用的列表解析结构如下：
[expression for target1 in iterable1 [if condition1]
? ?for target1 in iterable2 [if condition2]
? ?for target1 in iterable3 [if condition3]
? ?for target1 in iterable4 [if condition4]
? ?... .... ... .... ... ... ... ... ... ... ... ... ... ... .
??for targetN in iterableN [if conditionN]]
例如：
?
print rs == rx #True?
