Dpkg::Options {
<%- @_options.each_pair do |config, value| 
  if %w(force_confdef force_confold force_confnew force_confmiss).include?(config) then
    if value then -%>
  "--<%= config.sub('_','-') -%>";
    <%- end 
  else 
    scope.function_fail(["#{config} not a valid key for $unattended_upgrades::options"])
  end
end -%>
}