Sum of Missing Numbers

Create a function that returns the sum of missing numbers.

Examples

sum_missing_numbers([1, 3, 5, 7, 10]) ➞ 29
# 2 + 4 + 6 + 8 + 9

sum_missing_numbers([10, 7, 5, 3, 1]) ➞ 29

sum_missing_numbers([10, 20, 30, 40, 50, 60]) ➞ 1575

Notes

The minimum and maximum value of the given list are the inclusive bounds of the numeric range to consider when searching for missing numbers.