public static CDR fromTuple(Tuple t) {
   CDR cdr = new CDR();
   cdr.src = t.getString(0);
   cdr.dst = t.getString(1);
   cdr.start = t.getInteger(2);
   cdr.answer = t.getInteger(3);
   cdr.end = t.getInteger(4);
   cdr.disposition = t.getString(7);
   return cdr;
 }