You will be given an ordered list of individual integers. You need to return the list of integers as a string in a format of a range. But how do you explain a range? Well, according to this kata a list of integers can be written as a range if (1) the numbers in the given ordered list are consecutive on the number line, for example:- 1,2,3. (2) there are 3 or more than 3 consecutive numbers in the list.

What qualifies as a range?
[1,2,3,4] qualifies as a range and can be written as "1-4". (first and last elements are inclusive)
[6,7] does not qualify as a range, because there are less than 3 consecutive numbers in the list.
[9,10,11] qualifies as a range and can be written as "9-11".
[-3,-2,-1] qualifies as a range and can be written as "-3--1".

What you are supposed to do?
Given an ordered list of integers, if the integers can be written as a range then return them as range, else return them as integers separated by comma. You must return all the given integers in the list whether as a range (if it qualifies as a range) or just plain old integers.

For example:-

Input - [-6,-5,-4,0,2,6,10,11,13,14,15]
Output - "-6--4,0,2,6,10,11,13-15"
          |__|      |____| |__|
           |          |      |
  Qualifies as    Not a    is a range
  a range         range
                  (cuz only
                  two consecutive
                  numbers)

Input:- [1,3,5,7,9]
Output:- "1,3,5,7,9"

Input:- [1,2,3,4,5,6,7]
Output:- "1-7"

Input:- [1,2,3,8,9,10]
Ouput:- "1-3,8-10"

I hope this helps.