Question 4

A program runs `a = b = list()` and then `a.append(7)`. What is the value of `b`?

It is an empty list because `b` received a copy.
It is `None` because append has no list result.
Reading `b` raises NameError.
It is `[7]` because both names share one list.Correct answer

Explanation

The chained assignment evaluates `list()` once and binds both names to that one list. Appending through `a` mutates the shared object, so expecting `b` to remain empty incorrectly assumes that the constructor ran separately for each target.

Explanation

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