%Tc@s-dZddlmZdddYZdS(s*A class for storing chains of nucleotides.i(tSuitetChaincBseZdZd dZedZdZdZdZ dZ dZ dZ d Z d Zd Zd ZRS(s`A class for storing chains of nucleotides (which must all be instances of the nucleotide class).cCspi|_|dk r]xKt|D]4\}}||_||_||jt|js