def initialize(context):
    """
    Set up algorithm.
    """
    # https://www.quantopian.com/help#available-futures
    context.markets = [
        continuous_future('US'),
        continuous_future('TY'),
        continuous_future('SB'),
        continuous_future('SF'),
        continuous_future('BP'),
        continuous_future('JY'),
        continuous_future('CD'),
        continuous_future('SP'),
        continuous_future('ED'),
        continuous_future('TB'),
        continuous_future('GC'),
        continuous_future('SV'),
        continuous_future('HG'),
        continuous_future('CL'),
        continuous_future('HO'),
        continuous_future('HU')
    ]

def handle_data(context, data):
    """
    Process data every minute.
    """
    log.info(context.markets)
def initialize(context):
    """
    Set up algorithm.
    """
    # https://www.quantopian.com/help#available-futures
    context.markets = [
        continuous_future('US'),
        continuous_future('TY'),
        continuous_future('SB'),
        continuous_future('SF'),
        continuous_future('BP'),
        continuous_future('JY'),
        continuous_future('CD'),
        continuous_future('SP'),
        continuous_future('ED'),
        continuous_future('TB'),
        continuous_future('GC'),
        continuous_future('SV'),
        continuous_future('HG'),
        continuous_future('CL'),
        continuous_future('HO'),
        continuous_future('HU')
    ]

def before_trading_start(context, data):
    """
    Process data before every market open.
    """
    markets = context.markets[:]
    
    for market in markets:
        if market.end_date < get_datetime():
            context.markets.remove(market)
            log.info(
                '%s stopped trading. Deleted from markets.'
                % market.root_symbol
            )
            
    assert(len(context.markets) == 14)

def handle_data(context, data):
    """
    Process data every minute.
    """
    pass
Delete markets that stopped trading.
Delete markets that stopped trading.

  def initialize(context):
      """
      Set up algorithm.
      """
      # https://www.quantopian.com/help#available-futures
      context.markets = [
          continuous_future('US'),
          continuous_future('TY'),
          continuous_future('SB'),
          continuous_future('SF'),
          continuous_future('BP'),
          continuous_future('JY'),
          continuous_future('CD'),
          continuous_future('SP'),
          continuous_future('ED'),
          continuous_future('TB'),
          continuous_future('GC'),
          continuous_future('SV'),
          continuous_future('HG'),
          continuous_future('CL'),
          continuous_future('HO'),
          continuous_future('HU')
      ]
  
+ def before_trading_start(context, data):
+     """
+     Process data before every market open.
+     """
+     markets = context.markets[:]
+     
+     for market in markets:
+         if market.end_date < get_datetime():
+             context.markets.remove(market)
+             log.info(
+                 '%s stopped trading. Deleted from markets.'
+                 % market.root_symbol
+             )
+             
+     assert(len(context.markets) == 14)
+ 
  def handle_data(context, data):
      """
      Process data every minute.
      """
-     log.info(context.markets)
+     pass
Delete markets that stopped trading.
## Code Before:
def initialize(context):
    """
    Set up algorithm.
    """
    # https://www.quantopian.com/help#available-futures
    context.markets = [
        continuous_future('US'),
        continuous_future('TY'),
        continuous_future('SB'),
        continuous_future('SF'),
        continuous_future('BP'),
        continuous_future('JY'),
        continuous_future('CD'),
        continuous_future('SP'),
        continuous_future('ED'),
        continuous_future('TB'),
        continuous_future('GC'),
        continuous_future('SV'),
        continuous_future('HG'),
        continuous_future('CL'),
        continuous_future('HO'),
        continuous_future('HU')
    ]

def handle_data(context, data):
    """
    Process data every minute.
    """
    log.info(context.markets)
## Instruction:
Delete markets that stopped trading.
## Code After:
def initialize(context):
    """
    Set up algorithm.
    """
    # https://www.quantopian.com/help#available-futures
    context.markets = [
        continuous_future('US'),
        continuous_future('TY'),
        continuous_future('SB'),
        continuous_future('SF'),
        continuous_future('BP'),
        continuous_future('JY'),
        continuous_future('CD'),
        continuous_future('SP'),
        continuous_future('ED'),
        continuous_future('TB'),
        continuous_future('GC'),
        continuous_future('SV'),
        continuous_future('HG'),
        continuous_future('CL'),
        continuous_future('HO'),
        continuous_future('HU')
    ]

def before_trading_start(context, data):
    """
    Process data before every market open.
    """
    markets = context.markets[:]
    
    for market in markets:
        if market.end_date < get_datetime():
            context.markets.remove(market)
            log.info(
                '%s stopped trading. Deleted from markets.'
                % market.root_symbol
            )
            
    assert(len(context.markets) == 14)

def handle_data(context, data):
    """
    Process data every minute.
    """
    pass