class_docstr: Abstract Class for Stacks.
class_docstr_tok: ["Abstract","Class","for","Stacks","."]
code: def __str__(self):
      result = " ".join(map(str, self))
      return "Top-> " + result
  
imports: from abc import ABCMeta, abstractmethod
label_desc: Use image node_id 3 for calling the AbstractStack obj's underlying member method code with example usage: obj.__str__() and returns: unknown