code: protected <T extends Number> Gauge<T> createColumnFamilyGauge(final String name, Gauge<T> gauge)
      {
          return createColumnFamilyGauge(name, gauge, new Gauge<Long>()
          {
              public Long value()
              {
                  long total = 0;
                  for (Metric cfGauge : allColumnFamilyMetrics.get(name))
                  {
                      total = total + ((Gauge<? extends Number>) cfGauge).value().longValue();
                  }
                  return total;
              }
          });
      }
docs: Create a gauge that will be part of a merged version of all column families.  The global gauge
  will merge each CF gauge by adding their values