Include pairtools protocol about hic HOT 3 OPEN

       ext.args = { [
            "(mapq1>${params.min_mapq} and mapq2>${params.min_mapq})",
            params.min_cis_dist > 0 ? " and (abs(pos1-pos2) < ${params.min_cis_dist})" : '',
            params.keep_multi ? " and ((pair_type=='UU') or (pair_type=='UR') or (pair_type=='RU') or (pair_type=='MM') or (pair_type=='MU'))" : 
                                " and ((pair_type=='UU') or (pair_type=='UR') or (pair_type=='RU'))",
            params.dnase ? '' : " and (abs(int(rfrag1) - int(rfrag2)) > 1)",
            //params.min_insert_size > 0 ?  " and ( (rfrag_end1 - r1pos) + (rfrag_end2 - r2pos)) > ${params.min_insert_size}" : '',
            //params.max_insert_size > 0 ? " and ( (rfrag_end1 - r1pos) + (rfrag_end2 - r2pos)) < ${params.max_insert_size}" : '',
            //params.min_restriction_fragment_size > 0 ? " -t ${params.min_restriction_fragment_size}" : '',
            //params.max_restriction_fragment_size > 0 ? " -m ${params.max_restriction_fragment_size}" : '',
        ].join(' ').trim() }