input: Write a python function to find the maximum value in a list of numbers.
  assert maxValue([1, 4, 6, 2, -5, 10]) == 10
  assert maxValue([10, 20, 30, 5, 0]) == 30
  assert maxValue([-1, -3, -10, -2, -7]) == -1
output: def maxValue(numbers):
      if not numbers:
          return None  # Handle the case for an empty list
      max_val = numbers[0]
      for number in numbers:
          if number > max_val:
              max_val = number
      return max_val