What wrong did i do? (key in hashtable is always null)

[The Anh Tran]

This is just a small D exercise. I port c++ knucleotide from 
shootout.alioth.debian.org

Issue 1:
If i manually listing hashtable contents, the key does exist in that ht.
But (key in hash_table) always yield null.
Worse, if i use: "auto val = ht[key]", an exception is thrown.

Problem code is from line 163 to 177.


Issue 2:
If I pass an AA (uint[ulong]) to a template function.
DMD complains that uint[ulong] is void.
How can i get the type of AA?

DMD 2.037. Linux Ubuntu.
Source code:
ftp://ftp.4utours.com/dualamd/Dlang/knu5.d
Sample data:
ftp://ftp.4utours.com/dualamd/Dlang/fa50k.txt

Thanks.