code: def issequence(arg):
      
      string_behaviour = (
          isinstance(arg, six.string_types) or
          isinstance(arg, six.text_type))
      list_behaviour = hasattr(arg, '__getitem__') or hasattr(arg, '__iter__')
      return not string_behaviour and list_behaviour
docs: Return True if `arg` acts as a list and does not look like a string.