input: from typing import List
  
  def predict_next_stock_price(stock_prices: List[float]) -> float:
      """Given a trajectory of stock prices, predict the stock price for the next day.
      >>> predict_next_stock_price([10, 10.4, 10.5, 10.6, 10.7, 10.9, 11])
      11.0
      """
      return sum(stock_prices) / len(stock_prices)
output:     return sum(stock_prices) / len(stock_prices)