@Override
    protected void onSerialize(Serializer buf) {
        super.onSerialize(buf);
        buf.putDouble(null, waitTime);
        byte tmp = busyWait ? (byte)1 : (byte)0;
        buf.putByte(null, tmp);
    }
Constructs an instance of this class with given argument and wait parameters.

@param arg      The argument for this function.
@param waitTime The time to wait before executing expression.
@param busyWait true if busy wait, false if not.
searchlib/src/main/java/com/yahoo/searchlib/expression/DebugWaitFunctionNode.java