input: Write a python function to get the live stock price of a given stock symbol.
  assert round(get_stock_price('AAPL'), 2) > 0
  assert round(get_stock_price('MSFT'), 2) > 0
  assert round(get_stock_price('GOOGL'), 2) > 0
output: import requests
  
  def get_stock_price(symbol):
      api_key = 'YOUR_API_KEY'  # You need to replace 'YOUR_API_KEY' with a valid API key.
      url = f'https://www.alphavantage.co/query?function=GLOBAL_QUOTE&symbol={symbol}&apikey={api_key}'
      response = requests.get(url)
      data = response.json()
      return float(data['Global Quote']['05. price'])