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