input: def find_maximum_value(lst: list):
      """Find and return the largest value in the given list.
      >>> find_maximum_value([1, 2, 3])
      3
      >>> find_maximum_value([5, 3, -5, 2, -3, 3, 9, 0, 123, 1, -10])
      123
      """
output:     if not lst:
          return None
      max_value = lst[0]
      for num in lst:
          if num > max_value:
              max_value = num
      return max_value