003-6kyu-Find-the-odd-int.py

# https://www.codewars.com/kata/54da5a58ea159efa38000836
import collections

def find_it(seq):
  if len( seq ) == 0:
    return None
  b = collections.Counter(seq)
  for c in b:
    if b[c] % 2 ==1:
      return c