code: def register_flags!
        answers_with_registered_flags = answers
        answers_with_registered_flags[:feature_flags] ||= StringifyHash.new
        new_flags = answers_with_registered_flags[:feature_flags]
  
        FLAGS.each do |flag|
          key = canonical_key(flag)
          value = flag?(key)
          if !new_flags.include?(key) && !value.nil?
            new_flags[key] = value
          end
        end
  
        options.merge!(
          :answers => answers_with_registered_flags
        ) if !new_flags.empty?
  
        options
      end
docs: Updates options[:answers][:feature_flags] with any environment variables
   found based on FLAGS, but if and only if they are not already present.
  
   (existing :answers take precedence)