pythonic way to convert variable to list

Question

I have a function whose input argument can either be an element or a list of elements. If this argument is a single element then I put it in a list so I can iterate over the

Answer 1

That is an ok way to do it (don't forget to include tuples).

However, you may also want to consider if the argument has a __iter__ method or __getitem__ method. (note that strings have __getitem__ instead of __iter__.)

hasattr(arg, '__iter__') or hasattr(arg, '__getitem__')

This is probably the most general requirement for a list-like type than only checking the type.