e method returns 1. In case of
error, the method returns <b><tt>nil</tt></b> followed by an error
message.
</p>

<p class="note">
Note: This method can only be called before any
datagram is sent through the UDP object, and only once. Otherwise,
the system automatically binds the object to all local interfaces
and chooses an ephemeral port as soon as the first datagram is
sent. After the local address is set, either automatically by the
system or explicitly by <tt>setsockname</tt>, it cannot be
changed.
</p>