es are discarded. If there are less then
<tt>size</tt> bytes available in the current datagram, the
available bytes are returned.
If <tt>size</tt> is omitted, the
compile-time constant <a href="socket.html#datagramsize">
<tt>socket._DATAGRAMSIZE</tt></a> is used
(it defaults to 8192 bytes). Larger sizes will cause a
temporary buffer to be allocated for the operation.
</p>

<p class="return">
In case of success, the method returns the
received datagram. In case of timeout, the method returns
<b><tt>nil</tt><