code: def from_obj(cls, cls_obj):
          
          if not cls_obj:
              return None
  
          typekey = cls.objkey(cls_obj)
          klass   = cls.entity_class(typekey)
          return klass.from_obj(cls_obj)
docs: Parse the generateDS object and return an Entity instance.
  
          This will attempt to extract type information from the input
          object and pass it to entity_class to resolve the correct class
          for the type.
  
          Args:
              cls_obj: A generateDS object.
  
          Returns:
              An Entity instance.