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