public long asLong() {
    if (this.count > 2 || v[1] < 0) {
      SqlMathUtil.throwOverflowException();
    }
    return (((long) v[1]) << 32L) | v[0];
  }
Returns the value of this object as long, throwing error if the value
exceeds long.

@return the value this object represents
common/src/java/org/apache/hadoop/hive/common/type/UnsignedInt128.java