# File lib/net/ssh/known-hosts.rb, line 84
    def add(host, key)
      dir = File.dirname(source)
      Dir.mkdir(dir, 0700) if !File.exists?(dir)

      File.open(source, "a") do |file|
        buffer = Net::SSH::Transport::OSSL::Buffer.new
        buffer.write_key(key)
        blob = [buffer.to_s].pack("m*").gsub(/\s/, "")
        file.puts "#{Array(host).join(',')} #{key.ssh_type} #{blob}"
      end
    end