23. implement LengthOfTuple<T>

  - accepted / - tried

Here is an easy problem, please implement LengthOfTuple<T> to return the length of tuple.

type A = LengthOfTuple<['B', 'F', 'E']> // 3
type B = LengthOfTuple<[]> // 0

Let's try to solve this problem within 5 minutes.

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