my $s = SOAP::Lite
   ->uri('World')
   ->proxy('http://localhost/soap/soapserver.cgi')
# vvvvvvvvvvvvvvvvvvvvvvvvvv
   ->GoodBye("Bad world")
   ->on_debug(sub{print@_});
# ^^^^^^^^^^^^^^^^^^^^^^^^^^
print $s->result();