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foreach $key (sort keys %couples) {print "$key is married to $couples{$key}\n"};
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foreach (sort keys %couples) {print "$_ is married to $couples{$_}\n"};
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for (sort keys %couples) {print "$_ is married to $couples{$_}\n"};
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print "$_ is married to $couples{$_}\n" for (sort keys %couples);