@Override
    public void visitMembers(ObjectVisitor visitor) {
        super.visitMembers(visitor);
        visitor.visit("numBits", numBits);
    }
Sets the number of bits to operate on.

@param numBits The number of bits.
@return This, to allow chaining.
searchlib/src/main/java/com/yahoo/searchlib/expression/UnaryBitFunctionNode.java