class_docstr: abstract of Frontend 
docstr: implementation func 
code: def call(self, *args, **kwargs):
      """implementation func"""
      raise NotImplementedError()
  
file_path: delta/delta/data/frontend/base_frontend.py
imports: import abc
  import delta.compat
  from delta.utils.hparam import HParams
label_desc: Use image node_id 2 for calling the ABCFrontend obj's underlying member method code with example usage: obj.call() without return types