the value of the receive operation <code>&lt;-ch</code> is the value received
from the channel <code>ch</code>. The channel direction must permit receive operations,
and the type of the receive operation is the element type of the channel.
The expression blocks until a value is available.
Receiving from a <code>nil</code> channel blocks forever.
A receive operation on a <a href="#Close">closed</a> channel can always proceed