Price from external

You should be familiar with Chainlink heartbeats to solve this challenge.

In particular, in the getTokenPrice() function the value of 4 hours - FOUR_HOUR_TIMEOUT for all heartbeats in general is fixed. However, Chainlink gives these values for different tokens differently. For example, for stablecoins, this value is 24 hours. So the function will actually not work 20 hours a day and will return 0.