Something like this, perhaps?

(my $label_colnum = &column_exists( \@data, $_[1] || 0 )) == -1 and di
+e;
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Note that you don't test for definedness with ||, but for truth -- so that "" || 0 is also 0. But you already knew that, right?

The Sidhekin
print "Just another Perl ${\(trickster and hacker)},"