It says chaining, not concatenating. 
my $re = qr!yes|no!;
my $re2 = qr!${re}\sthankyou!;
print "polite yes or no\n" if "yes thankyou" =~ $re2;

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Makeshifts last the longest.

In reply to Re^6: regex "o" modifier ("chaining") by Aristotle
in thread regex "o" modifier by shemp

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