input: Write a python function to find the most frequent element in a list.
  assert frequency_selector([5, 2, 8, 7, 2, 2, 4]) == 2
  assert frequency_selector([1, 1, 2, 3, 4, 1, 2, 2, 1]) == 1
  assert frequency_selector(['a', 'b', 'b', 'b', 'c', 'a', 'a', 'b']) == 'b'
output: def frequency_selector(lst):
      from collections import Counter
      counter = Counter(lst)
      most_common_element, _ = counter.most_common(1)[0]
      return most_common_element