input: Write a python function to get the latest stock price for a given ticker symbol from Alpha Vantage.
  assert isinstance(get_stock_price('GOOGL'), str)
  assert isinstance(get_stock_price('MSFT'), str)
  assert get_stock_price('FAKE') is None
output: def get_stock_price(ticker):
      import requests
  
      api_key = 'YOUR_ALPHA_VANTAGE_API_KEY'
      base_url = 'https://www.alphavantage.co/query'
      
      params = {
          'function': 'TIME_SERIES_INTRADAY',
          'symbol': ticker,
          'interval': '1min',
          'apikey': api_key
      }
      
      response = requests.get(base_url, params=params)
      data = response.json()
      
      try:
          latest_time = sorted(data['Time Series (1min)'].keys())[0]
          latest_price = data['Time Series (1min)'][latest_time]['1. open']
          return latest_price
      except KeyError:
          return None