[Tutor] how to unittest cli input

[Alex Kleider]

On 2015-10-11 14:52, Cameron Simpson wrote:

> Minor remark: I would write "if src is not None:". In principle the
> empty string is also "falsey" like None, making your plain "if src:"
> slightly unreliable. Be precise!

'precise' is good!

Any comments about when/if to use 'if src != None:' vs 'if src is not 
None:'?
(or 'if src == None:' vs 'if src is None:')