bools mis-classified as ints when using `tx_obj`

[robberwick]

While writing tests for tx_obj, I noticed that attempting to call tx_obj(True) resulted in incorrect values being inserted in tx_buff

The culprit is the ordering of the instance type tests. For historic reasons, bool is a subclass of int, so True is an instance of int. (Originally, Python had no bool type, and things that returned truth values returned 1 or 0). Thus, as isinstance(val, int) is performed before isinstance(val, bool), the True is misidentified as an int. Swapping the order of operations fixes this problem.