Go - unidirectional channel

• Send only: chan<- int
• Receive only: <-chan int
  
• Violation will compile error
  
• Only channel used to send msg need to be closed, so to close a receive only channel will compile error
• A channel can be passed as an unidirectional channel. So that can be foced to use it correctly in function.
  
• Can convert a bidirectional channel to unidirectional, but not vice versa