Tip: Understand Golang Channel Directions

• Channel is used to communicate among Goroutines.
• Always image a channel as a pipe in the brain. A pipe of any concrete type of Golang, like string, int..etc. This pipe connects Goroutines
• There is sending side of this pipe on one Goroutines, and there is an ending side of this pipe on another Goroutines
• main() is also a Goroutine. 
• We need to identify which Goroutine is sending side, which is the ending side.

• Sending side is like.

sends chan<- string 

the chan<- string  means there is a string on the sending side of pipe   
We use it like    sends <- "my sending string" 
Ending side is like.
ends <-chan string 
the <-chan string  means there is a string on the ending side of pipe   
We use it like    ending_message <-ends or <-ends
for range <channel name>: it's used on the ending side the pipe to fetch values
time.Ticker is a good example of ending side of pipe
type Ticker struct {
	C <-chan Time // The channel on which the ticks are delivered.
	// contains filtered or unexported fields
}

Below is another advance example of sending / ending side
os.Signal is the sending side of channel sigs
another process or thread from OS
main() goroutines is the ending side of channel sigs
// Registering signals - INT and TERM
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
// Process blocked here and waiting for signal(term/int)
<-sigs