input: Write a python function to manage a stock trading system using the provided `StockTrader` class.
  ```python
  assert trader.check_balance() == 0
  assert trader.stocks == {}
  
  trader.buy_stock('AAPL', 10)
  assert trader.stocks == {'AAPL': 10}
  assert trader.balance == -10
  
  trader.sell_stocks('AAPL', 5)
  assert trader.stocks == {'AAPL': 5}
  assert trader.balance == -5
  
  trader.sell_stocks('AAPL', 10)  # This should print "Not enough AAPL purchased to sell"
  assert trader.stocks == {'AAPL': 5}
  assert trader.balance == -5
  
  trader.sell_stocks('GOOG', 5)  # This should print "You do not own any GOOG"
  assert trader.stocks == {'AAPL': 5}
  assert trader.balance == -5
output: class StockTrader:
      def __init__(self):
          self.balance = 0
          self.stocks = {}
  
      def check_balance(self):
          return self.balance
  
      def buy_stock(self, ticker, quantity):
          if ticker in self.stocks:
              self.stocks[ticker] += quantity
          else:
              self.stocks[ticker] = quantity
          self.balance -= quantity
  
      def sell_stocks(self, ticker, quantity):
          if ticker not in self.stocks:
              print(f"You do not own any {ticker}")
          elif self.stocks[ticker] < quantity:
              print(f"Not enough {ticker} purchased to sell")
          else:
              self.stocks[ticker] -= quantity
              self.balance += quantity
              if self.stocks[ticker] == 0:
                  del self.stocks[ticker]
  
  trader = StockTrader()