# Closing channels in Go

Channels can be explicitly closed by a *sender*:

```go
ch := make(chan int)

// do some stuff with the channel

close(ch)
```

## Checking if a channel is closed

Similar to the `ok` value when accessing data in a `map`, receivers can check the `ok` value when receiving from a channel to test if a channel was closed.

```go
v, ok := <-ch
```

ok is `false` if the channel is empty and closed.

## Don't send on a closed channel

Sending on a closed channel will cause a panic. A panic on the main goroutine will cause the entire program to crash, and a panic in any other goroutine will cause *that goroutine* to crash.

Closing isn't necessary. There's nothing wrong with leaving channels open, they'll still be garbage collected if they're unused. You should close channels to indicate explicitly to a receiver that nothing else is going to come across.

## Assignment

At Mailio we're all about keeping track of what our systems are up to with great logging and [telemetry](https://en.wikipedia.org/wiki/Telemetry).

The `sendReports` function sends out a batch of reports to our clients and reports back how many were sent across a channel. It closes the channel when it's done.

Complete the `countReports` function. It should:

* Use an infinite `for` loop to read from the channel:
* If the channel is closed, break out of the loop
* Otherwise, keep a running total of the number of reports sent
* Return the total number of reports sent