code: def verify(self, obj):
          
  
          if not isinstance(obj, str):
              raise ValidationError("Object is not a string", reason='object is not a string',
                                    object=obj, type=type(obj), str_type=str)
  
          return obj
docs: Verify that the object conforms to this verifier's schema
  
          Args:
              obj (object): A python object to verify
  
          Raises:
              ValidationError: If there is a problem verifying the dictionary, a
                  ValidationError is thrown with at least the reason key set indicating
                  the reason for the lack of validation.