If the capacity is zero or absent, the channel is unbuffered and communication
succeeds only when both a sender and receiver are ready. Otherwise, the channel
is buffered and communication succeeds without blocking if the buffer
is not full (sends) or not empty (receives).
A <code>nil</code> channel is never ready for communication.
</p>

<p>
A channel may be closed with the built-in function

If the capacity is zero or absent, the channel is unbuffered and communication
succeeds only when both a sender and receiver are ready. Otherwise, the channel
is buffered and communication succeeds without blocking if the buffer
is not full (sends) or not empty (receives).
A <code>nil</code> channel is never ready for communication.
</p>

<p>
A channel may be closed with the built-in function