code: def deprecated(extra):
      
      def decorator(func):
          """
          Return a decorated function that emits a deprecation warning on use.
          """
          @wraps(func)
          def wrapper(*args, **kwargs):
              """
              Wrap the function.
              """
              message = 'You called the deprecated function `{function}`. {extra}'.format(
                  function=func.__name__,
                  extra=extra
              )
              frame = inspect.currentframe().f_back
              warnings.warn_explicit(
                  message,
                  category=DeprecationWarning,
                  filename=inspect.getfile(frame.f_code),
                  lineno=frame.f_lineno
              )
              return func(*args, **kwargs)
          return wrapper
      return decorator
docs: Flag a method as deprecated.
  
      :param extra: Extra text you'd like to display after the default text.