def _retranslate(seq):
        '''
        Retranslates a nucleotide sequence following refinement.
        Input is a Pair sequence (basically a dict of MongoDB output).
        '''
        if len(seq['vdj_nt']) % 3 != 0:
            trunc = len(seq['vdj_nt']) % 3
            seq['vdj_nt'] = seq['vdj_nt'][:-trunc]
        seq['vdj_aa'] = Seq(seq['vdj_nt'], generic_dna).translate()