input: Write a function to filter a list of integers to keep only those greater than 50 using a lambda expression.
  assert filtered_list([45, 12, 52, 89, 33, 99])==[52, 89, 99]
  assert filtered_list([51, 52, 50, 49])==[51, 52]
  assert filtered_list([50, 50, 50, 50])==[]
  assert filtered_list([])==[]
output: def filtered_list(lst):
      return list(filter(lambda x: x > 50, lst))