eval {
    $self->find($foo);
}; if ($@) {
    if ($@->isa('Signal::Search')
    {
        if ($@->isa('Signal::Search::Found'))
        {
            print "found";
        }
        else
        {
            print "Not found";
        }
    }
    else # These are (presumably) error conditions ...
    {
        # Handle error here.
    }
}