Nullish coalescing
The null coalescing operator looks very similar to the or
operation, but a or b
is equivalent to a if a else b
, and a ?? b
is equivalent to a if a is None else b
. The difference between the two is that a ?? b
judges the value of None
, while a or b
judges all false values (such as: ""
, False
, 0
, []
, {}
, etc.).
Grammar
1 

Priority
??
has the same priority as or
.
Notice
The priority between ??
and or
is undetermined, so it cannot be used directly in chain. When you want ??
and or
to appear in the same expression, then you need to put parentheses around them, otherwise a syntax error will be thrown.
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Reference
 https://peps.python.org/pep0505/