```ruby
#
# Cookbook Name:: sys
# Recipe:: nftables
#
# Copyright 2014, HPC Team
#

unless node['sys']['nftables'].empty?

  if node['debian'] && node['debian']['codename'] && node['debian']['codename'].eql?('stretch')

    
  end
end
```

Add a comment and emit a warning
user
```ruby
#
# Cookbook Name:: sys
# Recipe:: nftables
#
# Copyright 2014-2022 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH
#
# Authors:
#  Matthias Pausch   <m.pausch@gsi.de>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

# this recipe has been superseded by sys::firewall
return unless node['sys']['nftables']

Chef::Log.warn('The sys::nftables recipe has been removed. Use sys::firewall instead')
```
assistant