code: def _add_cors(self):
          
  
          INVALID_ERROR = "Invalid value for 'Cors' property"
  
          if not self.cors:
              return
  
          if self.cors and not self.definition_body:
              raise InvalidResourceException(self.logical_id,
                                             "Cors works only with inline Swagger specified in "
                                             "'DefinitionBody' property")
  
          if isinstance(self.cors, string_types) or is_instrinsic(self.cors):
              # Just set Origin property. Others will be defaults
              properties = CorsProperties(AllowOrigin=self.cors)
          elif isinstance(self.cors, dict):
  
              # Make sure keys in the dict are recognized
              if not all(key in CorsProperties._fields for key in self.cors.keys()):
                  raise InvalidResourceException(self.logical_id, INVALID_ERROR)
  
              properties = CorsProperties(**self.cors)
  
          else:
              raise InvalidResourceException(self.logical_id, INVALID_ERROR)
  
          if not SwaggerEditor.is_valid(self.definition_body):
              raise InvalidResourceException(self.logical_id, "Unable to add Cors configuration because "
                                                              "'DefinitionBody' does not contain a valid Swagger")
  
          if properties.AllowCredentials is True and properties.AllowOrigin == _CORS_WILDCARD:
              raise InvalidResourceException(self.logical_id, "Unable to add Cors configuration because "
                                                              "'AllowCredentials' can not be true when "
                                                              "'AllowOrigin' is \"'*'\" or not set")
  
          editor = SwaggerEditor(self.definition_body)
          for path in editor.iter_on_path():
              editor.add_cors(path, properties.AllowOrigin, properties.AllowHeaders, properties.AllowMethods,
                              max_age=properties.MaxAge, allow_credentials=properties.AllowCredentials)
  
          # Assign the Swagger back to template
          self.definition_body = editor.swagger
docs: Add CORS configuration to the Swagger file, if necessary