python - Case insensitive 'in'

Question

I love using the expression

if 'MICHAEL89' in USERNAMES:
    ...

where USERNAMES is a list.

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Is there any way to match items with case insensitivity or do I need to use a custom method? Just wondering if there is a need to write extra code for this.

Answer 1

username = 'MICHAEL89'
if username.upper() in (name.upper() for name in USERNAMES):
    ...

Alternatively:

if username.upper() in map(str.upper, USERNAMES):
    ...

Or, yes, you can make a custom method.