code: def collect(cls):
          
          constants = {}
  
          for method_path in WebpackConstants.get_constant_processors():
              method = import_string(method_path)
  
              if not callable(method):
                  raise ImproperlyConfigured('Constant processor "%s" is not callable' % method_path)
  
              result = method(constants)
  
              if isinstance(result, dict):
                  constants.update(result)
  
          return constants
docs: Load all constant generators from settings.WEBPACK_CONSTANT_PROCESSORS
              and concat their values.