EXPORTED FUNCTION
 bisect
     my ($a,$b) = bisect {$_ <= 5} 1..10;
     # $a == [1..5]
     # $b == [6..10]

   Useage is like grep where you pass it a block and a list, returns a list
   of two arrayrefs. All TRUE values are put in to the first arrayref,
   FALSE in the second arrayref.

 trisect
     my ($a,$b,$c) = trisect {$_ <=> 5} 1..10;
     # $a == [1..4]
     # $b == [5]
     # $c == [6..10]

   Useage is like grep where you pass it a block and a list, returns a list
   of three arrayrefs. The intent here though is to break that list in to
   three parts using cmp-style returns (-1/0/1). All values that cause your
   codeblock to return -1 are in the first arrayref, 0 in the next, and
   everything else falls in the last arrayref.

   !!NOTE!! Currently the last arrayref is a catch all for anything that
   does not exactly match -1/0. If you write your own cusom block that
   returns any value other then -1/0/1 then it will end up here. This was
   done as I want to keep the expectation that all items from the input
   list will be found some where in the output.

     my ($x,$y,$z) = trisect { $_ < 5 ? -1
                             : $_ > 5 ? 1
                             : 'foo'
                             } 1..10;
     # $x == [1..4]
     # $y == []
     # $z == [5..10]