In this task, you are given a question. You have to answer the question based on your information.

Let me give you an example: Roman Yakub won first price in a Choral Composition Competition at a liberal arts college founded by who?
The answer to this example can be: William Egbert
Here is why: This is a good example, and output correctly answers the question.

OK. solve this:
The city of Gavle received its charter during which era?
Answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
era of the Kalmar Union