return the 'empty list' right away? Wouldn't that be ()?

It seems to be speaking abstractly. It's speaking of the list of results, and not of the data format used to represent the list of results.

find_share actually returns a reference to an array containing the list of results. So where the documentation says an empty list (of results) is returned, the implementation returns a reference to an empty array.

my $share_1 = find_share($total/2, [@_]);

if (!@$share_1) {
   print("No results\n");
}
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