The code labelled “Block 2” does not correspond directly to any code in the recursive function; it is pure incidental complexity. When we find ourselves processing a FoldTreeFrame it may be because we are entering it for the first time after a parent call created it, or it may be because we are re-entering it after a child frame’s execution completed. This means that, before we make a recursive call in block 3, we need to check whether that call has already been completed. If so, we run whatever logic should happen after the recursive call. In this case there is no such logic in foldTree so we only need to deal with the mechanical concerns of returning to our parent frame.
each other in useful ways.
，详情可参考新收录的资料
m{a-z ` ' [] *}。业内人士推荐新收录的资料作为进阶阅读
That fixed geometry turned out to be a huge win, because it made the reverse direction almost，详情可参考新收录的资料