public TruthValue not() {
      switch (this) {
        case NO:
          return YES;
        case YES:
          return NO;
        case NULL:
        case YES_NO:
        case YES_NO_NULL:
          return this;
        case NO_NULL:
          return YES_NULL;
        case YES_NULL:
          return NO_NULL;
        default:
          throw new IllegalArgumentException("Unknown value: " + this);
      }
    }
Compute logical AND between the two values.
@param right the other argument or null
@return the result
storage-api/src/java/org/apache/hadoop/hive/ql/io/sarg/SearchArgument.java