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Number Sum
In this chapter we are going to hammer down the concepts we've learned by running through a bunch of practice problems without introducing any new concepts.
Assignment
Complete the number_sum function. It should add up all the numbers from 1 to n and return the result. If n is less than 1, return 0. For example:
number_sum(5) -> 1+2+3+4+5 -> 15number_sum(3) -> 1+2+3 -> 6
Remember that a range will not include the last number.