Once execution returns to the original sumTree invocation, it executes sumTree(tree.right). Again, it remembers its place in the function.
and deleted line indicators in the margin, like diff-hl or，更多细节参见新收录的资料
장동혁 “의원들 의견 잘 들었다”…‘절윤’ 입장 이틀째 침묵，详情可参考新收录的资料
※반드시 전문의를 찾아야 할 신호
use-package block in here has :ensure nil, because it's pointing