input: Write a function to find the maximum element in the given array. The function should take a list as input and return the maximum element in that list.
  assert find_max_element([1, 10, 50, 3, 8])==50
  assert find_max_element([2, 4, 6, 8, 10])==10
  assert find_max_element([-5, -2, -1, -10])==-1
  assert find_max_element([0, 0, 0, 0])==0
  assert find_max_element([])==None
output: def find_max_element(arr):
      if not arr:
          return None
      max_element = arr[0]
      for num in arr:
          if num > max_element:
              max_element = num
      return max_element