Test your knowledge: collections.Counter

Review

1. What does a Counter return when an absent key is read?

   A missing Counter key reads as zero; the lookup does not add the key.
2. What does most_common(2) return?

   most_common(n) returns a list of up to n (item, count) pairs in descending count order.
3. What happens when counts.update({'tea': 3}) is called for tea already counted as 2?

   Counter.update adds counts from a mapping rather than replacing the prior count.
4. Which counts does elements() emit?

   elements() ignores counts below one and uses positive integer counts to determine repetitions.
5. What does left & right mean for two Counter objects?

   Counter intersection keeps minimum counts and omits non-positive results.