Program execution begins by initializing the main package and then
invoking the function main.
-
When the function main returns, the program exits.
It does not wait for other (non-main) goroutines to complete.
+Package initialization—variable initialization and the invocation of
+init functions—happens in a single goroutine,
+sequentially, one package at a time.
+An init function may launch other goroutines, which can run
+concurrently with the initialization code. However, initialization
+always sequences
+the init functions: it will not start the next
+init until
+the previous one has returned.
+