Free Range

Create a function which converts an ordered number list into a list of ranges (represented as strings). Note how some lists have some numbers missing.

Examples

numbers_to_ranges([1, 2, 3, 4, 5]) ➞ ["1-5"]

numbers_to_ranges([3, 4, 5, 10, 11, 12]) ➞ ["3-5", "10-12"]

numbers_to_ranges([1, 2, 3, 4, 99, 100]) ➞ ["1-4", "99-100"]

numbers_to_ranges([1, 3, 4, 5, 6, 7, 8]) ➞ ["1", "3-8"]

Notes

• If there are no numbers consecutive to a number in the list, represent it as only the string version of that number (see example #4).
• Return an empty list if the given list is empty.