sub send {
    @_ >= 2 && @_ <= 4 or croak 'usage: $sock->send(BUF, [FLAGS, [TO]])';
    my $sock  = $_[0];
    my $flags = $_[2] || 0;
    my $peer  = $_[3] || $sock->peername;

    croak 'send: Cannot determine peer address'
	 unless($peer);