[rtags] Allow to 'derive' rtags Since some releases, rtags (structure underlying uicfg) have selector and may be copied using something like: new_rtags = deepcopy(original_rtags) new_rtags.__module__ = __name__ new_rtags.__select__ = custom_selector The problem is that starting from that, both rtags wil diverge and changes in original_rtags won't be considered, while we usually want to set a few specific rules only in new_rtags. To fix this problem, this cset introduces the notion of "derivated/parent" rtag, eg: new_rtags = original_rtags.derive(__name__, custom_selector) Beside easier copying, when using the above method changes in original_rtags which are not overriden by new_rtags will be considered since it only hold its specific rules but look among its parent chain for non-found keys. Along the way, flake8 unittest_rtags. Closes #16164880

function datetuple(d) {
    return [d.getFullYear(), d.getMonth()+1, d.getDate(), 
	    d.getHours(), d.getMinutes()];
}
    
function pprint(obj) {
    print('{');
    for(k in obj) {
	print('  ' + k + ' = ' + obj[k]);
    }
    print('}');
}

function arrayrepr(array) {
    return '[' + array.join(', ') + ']';
}
    
function assertArrayEquals(array1, array2) {
    if (array1.length != array2.length) {
	throw new crosscheck.AssertionFailure(array1.join(', ') + ' != ' + array2.join(', '));
    }
    for (var i=0; i<array1.length; i++) {
	if (array1[i] != array2[i]) {
	    
	    throw new crosscheck.AssertionFailure(arrayrepr(array1) + ' and ' + arrayrepr(array2)
						 + ' differs at index ' + i);
	}
    }
}