This is a FAQ. 
use Hash::MultiKey;
tie my %valid, 'Hash::MultiKey';
%valid = (
    [qw(A q)] => 1,
    [qw(A u)] => 6,
    [qw(A k)] => 3,
    [qw(C t)] => 10,
    [qw(Z u)] => 30,
);

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In reply to Re: Two dimensional sets intersection by daxim
in thread Two dimensional sets intersection by menth0l

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