code: def deprecated(func):
      
      @functools.wraps(func)
      def new_func(*args, **kwargs):
          if sys.version_info < (3, 0):
              warnings.warn_explicit(
                  "Call to deprecated function {}.".format(func.__name__),
                  category=DeprecationWarning,
                  filename=func.func_code.co_filename,
                  lineno=func.func_code.co_firstlineno + 1
              )
          else:
              warnings.warn_explicit(
                  "Call to deprecated function {}.".format(func.__name__),
                  category=DeprecationWarning,
                  filename=func.__code__.co_filename,
                  lineno=func.__code__.co_firstlineno + 1
              )
          return func(*args, **kwargs)
      return new_func
docs: Mark functions as deprecated.
  
      It will result in a warning being emitted when the function is used.