code: def format_asset(asset):
      
  
      try:
          import zipline.assets
      except ImportError:
          return asset
  
      if isinstance(asset, zipline.assets.Asset):
          return asset.symbol
      else:
          return asset
docs: If zipline asset objects are used, we want to print them out prettily
      within the tear sheet. This function should only be applied directly
      before displaying.