code: public static long updateLong(long value, long range)
       {
           range = range == 0 ? (long)(0.1 * value) : range;
           long minValue = value - range;
           long maxValue = value + range;
           return nextLong(minValue, maxValue);
       }
docs: Updates (drifts) a long value within specified range defined
  
  @param value a long value to drift.
  @param range (optional) a range. Default: 10% of the value
  @return updated random long value.