input: Write a python function to filter half of the elements randomly from a list.
  assert len(filter_half_array([9, 2, 7, 4, 5, 6, 8, 1, 4, 0])) == 0
  assert len(filter_half_array([1, 2, 3, 4, 5, 6])) == 0
  assert filter_half_array([]) == []
output: import random
  
  def filter_half_array(lst):
      if not lst:
          return []
      half_length = len(lst) // 2
      return random.sample(lst, half_length)