code: def extract_blocking(obj):
      
      if isinstance(obj, tuple):
          try:
              a, b = obj
          except:
              raise TypeError("Not a Blocking object")
      else:
          a, b = obj, None
      return extract_attr(a, keys=["Index"]), b
docs: Extract index and watch from :class:`Blocking`
  
      Parameters:
          obj (Blocking): the blocking object
      Returns:
          tuple: index and watch