public final DoubleWritable evaluate(DoubleWritable a) {
    if (a == null) {
      return null;
    }

    return doEvaluate(a);
  }
Returns {@code null} if the passed in value is {@code} and passes on to {@link #doEvaluate(DoubleWritable)} if not.
ql/src/java/org/apache/hadoop/hive/ql/udf/UDFMath.java