class_docstr: Base class of solver.
class_docstr_tok: ["Base","class","of","solver","."]
docstr: return Model class 
docstr_tok: ["return","Model","class"]
code: def model_fn(self):
      """return Model class"""
      classname = self.config["model"]["name"]
      logging.info("__name__=%s\tclassname==%s", __name__, classname)
  
      # Model initialization
      model = registers.model[classname](self.config)
      return model
  
imports: import abc
  import math
  import delta.compat
  import tensorflow_addons
  from absl import logging
  from delta import utils
  from delta.utils import optimizer
  from delta.utils.register import registers
label_desc: Use image node_id 5 for calling the Solver obj's underlying member method code with example usage: obj.model_fn() and returns: model