How to resolve string inequality

Question

In python a is:

a = "XPZC"

Why is following False in python?

(str(a)[:2] == ("YP" or "XP"))

Answer 1

This is because ("YP" or "XP") resolves to "YP" because it is asking to return whether "YP" or "XP" resolve to True.

In this case the 'or' is short circuited (since "YP" is not False, "XP" is not evaluated). It returns the non-False value of "YP" which is... "YP"

Also a[:2] is equal to XP. Also, you don't need to call str() since a is a string.

>>> a = "XPZC"
>>> a[:2]
'XP'
>>> "YP" or "XP"
'YP'

You probably want to use in:

>>> a[:2] in ("YP", "XP")
True

or, just check two conditions using or:

>>> s = a[:2]
>>> s == "YP" or s == "XP"
True

Answer 2

(str(a)[:2] in ["YP", "XP"])

"YP" or "XP" returns 'YP'