input: Write a function to print the maximum number from a given list.
  def max_num(nums):
      max = nums[0]
      for num in nums[1:]:
          if num > max:
              max = num
      print(max)
  
  nums = [5, 4, 2, 7, 12]
  max_num(nums)
output: def max_num(nums):
      max = nums[0]
      for num in nums[1:]:
          if num > max:
              max = num
      print(max)