$seq1 = 'AAAACCCCGGGGTTTT';
$seq2 = 'ACGTACGTACGTACGT';

##</code><code>##

{  
    A2C => 1,  A2G => 1,  A2T => 1,  C2A => 1,  C2G => 1,  C2T => 1,  
    G2A => 1,  G2C => 1,  G2T => 1,  T2A => 1,  T2C => 1,  T2G => 1,
}

##</code><code>##

A2G=1; G2A=1; C2T=1; T2C=1; A2T=1; A2C=1; G2T=1; G2C=1.