input: Write a function to find the first non-repeating character in a given list. The function should return the first unique element if found, otherwise return None.
  assert first_non_repeating_char([1, 2, 3, 4, 4, 3, 2, 1])==None
  assert first_non_repeating_char([5, 6, 7, 7, 5, 6, 8])==8
  assert first_non_repeating_char([9, 9, 9, 10, 10, 11])==11
  assert first_non_repeating_char([12, 13, 14, 15])==12
  assert first_non_repeating_char([16, 16, 17, 18, 18])==17
output: def first_non_repeating_char(lst):
      count = {}
      for item in lst:
          if item in count:
              count[item] += 1
          else:
              count[item] = 1
      for item in lst:
          if count[item] == 1:
              return item
      return None