def incrementer(nums):
    return [(n+i) % 10 for i,n in enumerate(nums,1)]

'''
Given an input of an array of digits num, return the
 array with each digit incremented by its position in
 the array. For example, the first digit will be incremented
 by 1, the second digit by 2 etc. Make sure to start counting
your positions from 1 and not 0.

incrementer({1,2,3}) => {2,4,6}

Your result can only contain single digit numbers, so if
 adding a digit with it's position gives you a multiple-digit
number, only the last digit of the number should be returned

incrementer({4,6,9,1,3}) => {5,8,2,5,8}

  - 9 + 3 (position of 9 in array) = 12 
  - Only its last digit 2 should be returned

Lastly, return {} if your array is empty! Arrays will only
 contain numbers so don't worry about checking that.

'''