At the point where you are doing your validation (or where you are doing the actual work with the variable) you can make that decision. It's entirely possible

At the point where you are doing your validation (or where you are doing the actual work with the variable) you can make that decision. It's entirely possible that upstream code is content with any type as long as it's coercible. A lot of Python code just wants an iterable, for example, or something that can be coerced to a string. It's definitely possible to have a situation where you need a string specifically (or an integer specifically), but it's generally better to have your code coerce the data whenever possible so as to allow for more logical code. e.g. 's.send(str(object))' (if object has a relevant __str__()) makes perfect sense in code. You don't necessarily need a string, you just need something that can behave as a string in a sensible manner. You also end up with scenarios where None is a 'valid value' in e.g. the SQL sense of 'value not specified'; for example, company_name might be '' (empty string provided) or None (no value provided); either way company_name is Falsey, and your logic should work the same.