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course/13-channels/exercises/4-buffered_channels/readme.md

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+# Buffered Channels
+
+Channels can *optionally* be buffered.
+
+## Creating a channel with a buffer
+
+You can provide a buffer length as the second argument to `make()` to create a buffered channel:
+
+```go
+ch := make(chan int, 100)
+```
+
+Sending on a buffered channel only blocks when the buffer is *full*. 
+
+Receiving blocks only when the buffer is *empty*.
+
+## Assignment
+
+We want to be able to send emails in *batches*. A *writing* goroutine will write an entire batch of email messages to a buffered channel, and later, once the channel is full, a *reading* goroutine will read all of the messages from the channel and send them out to our clients.
+
+Complete the `addEmailsToQueue` function. It should create a buffered channel with a buffer large enough to store all of the `emails` it's given. It should then write the emails to the channel in order, and finally return the channel.