input: Write a python function to find the maximum value in a list of numbers.
  assert find_max_value([21, 15, 11, 17, 12, 29]) == 29
  assert find_max_value([10, 20, 30, 40, 50]) == 50
  assert find_max_value([-10, -20, -30, -40, -50]) == -10
output: def find_max_value(numbers):
      max_value = numbers[0]
      for num in numbers:
          if num > max_value:
              max_value = num
      return max_value