Flatten list explicitly before mapping
Flatten list explicitly before mapping

... which not only replaces the discouraged use of flatmap, but also
gets this code working again.  The flatmap was giving incorrect
key/value results; the list needed to be explicitly flattened before the
map operation was to be used on the result.

perl6/perl6-examples,perl6/perl6-examples,perl6/perl6-examples,perl6/perl6-examples,perl6/perl6-examples