We'll pass you two numbers. Return the sum of those two numbers and all numbers between them. The lowest number will not always come first.
- sumAll(1, 4) should return a number.
- sumAll(1, 4) should return 10.
- sumAll(4, 1) should return 10.
- sumAll(5, 10) should return 45.
- sumAll(10, 5) should return 45.