input: Write a function to calculate the maximum revenue that can be obtained from a list of prices. The function should return the maximum difference between any two prices in the list. The function considers the list of prices as if you buy at one price and sell at another price later, and you are allowed to do multiple transactions, but we are interested in the maximum revenue that can be obtained from a single pair of buy and sell transactions.
  
  def max_revenue(prices):
      diff = [prices[i + 1] - prices[i] for i in range(len(prices) - 1)] 
      max_diff = 0
      for i in range(len(diff)): 
          for j in range(i + 1, len(diff) + 1): 
              current_diff = sum(diff[i:j]) 
              if current_diff > max_diff: 
                  max_diff = current_diff 
   
      return max_diff
output: def max_revenue(prices):
      if not prices:
          return 0
      min_price = prices[0]
      max_profit = 0
      for price in prices:
          if price < min_price:
              min_price = price
          else:
              max_profit = max(max_profit, price - min_price)
      return max_profit