让我们来分解一下：<start_function_call — 函数调用开始，call: — 前缀，change_background_color — 函数名，{color:<escapered<escape} — 带转义标记的参数，<end_function_call — 函数调用结束。
let totalBytes = 0;，详情可参考Line官方版本下载
[ anyVar isNil ifTrue: anyBlock ] bpattern ，这一点在Line官方版本下载中也有详细论述
In December I wrote about package managers using git as a database, and how Cargo’s index, Homebrew’s taps, Go’s module proxy, and CocoaPods’ Specs repo all hit the same wall once their access patterns outgrew what a git repo is designed for.，推荐阅读同城约会获取更多信息