input: Write a python function to find the most frequent element in a list.
  assert most_frequent([4, 8, 9, 4, 6, 4, 8]) == 4
  assert most_frequent([1, 2, 2, 3, 3, 3, 4]) == 3
  assert most_frequent([5, 5, 5, 6, 6, 7, 7, 7]) == 5
output: def most_frequent(lst):
      from collections import Counter
      count = Counter(lst)
      return count.most_common(1)[0][0]