code: public String summarize ()
      {
          StringBuilder buf = new StringBuilder();
          buf.append(_count).append(":");
          for (int ii = 0; ii < _buckets.length; ii++) {
              if (ii > 0) {
                  buf.append(",");
              }
              buf.append(_buckets[ii]);
          }
          return buf.toString();
      }
docs: Generates a terse summary of the count and contents of the values in this histogram.