input: Write a python function to find the maximum item in a list.
  assert get_maximum_item([1, 3, 7, 2, 5]) == 7
  assert get_maximum_item([-1, -3, -7, -2, -5]) == -1
  assert get_maximum_item([10, 20, 5, 15, 30]) == 30
  assert get_maximum_item([]) == float('-infinity')
output: def get_maximum_item(lst):
      if not lst:
          return float('-infinity')
      max_item = lst[0]
      for item in lst[1:]:
          if item > max_item:
              max_item = item
      return max_item