Multiple choice python

foo = {1:'1', 2:'2', 3:'3'} del foo[1] foo[1] = '10' del foo[2] print len(foo)

  1. 2

  2. 7

  3. 3

  4. 4

  5. An exception is thrown
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The code starts with a dictionary of 3 key-value pairs. After 'del foo[1]', only keys 2 and 3 remain. Then 'foo[1] = '10'' adds a new key 1. After 'del foo[2]', only keys 1 and 3 remain. So len(foo) returns 2. The key takeaway is that deleting and re-adding the same key is allowed - the old key-value pair is gone, and adding it back counts as a new key.

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