input: 
  from typing import List
  
  def max_of_three(numbers: List[float]) -> float:
      """ Find the maximum of three numbers given in a list.
      >>> max_of_three([3, 4, 5])
      5
      """
  
output:     if len(numbers) != 3:
          raise ValueError("The list must contain exactly three numbers.")
      
      return max(numbers)