text: '''
  QUESTION:
  389. Find the Difference
  
  Given two strings s and t which consist of only lowercase letters.
  
  String t is generated by random shuffling string s and then add one more letter at a random position.
  
  Find the letter that was added in t.
  
  Example:
  
  Input:
  s = "abcd"
  t = "abcde"
  
  Output:
  e
  
  Explanation:
  'e' is the letter that was added.
  
  '''
  
  from collections import Counter
  class Solution:
      def findTheDifference(self, s, t):
          return "".join( (Counter(t) - Counter(s)).keys() )
  
  '''
  Ideas/thoughts:
  return string of counters diff keys.
  
  '''