# File lib/em/connection.rb, line 406
    def start_tls args={}
      priv_key, cert_chain, verify_peer = args.values_at(:private_key_file, :cert_chain_file, :verify_peer)

      [priv_key, cert_chain].each do |file|
        next if file.nil? or file.empty?
        raise FileNotFoundException,
        "Could not find #{file} for start_tls" unless File.exists? file
      end

      EventMachine::set_tls_parms(@signature, priv_key || '', cert_chain || '', verify_peer)
      EventMachine::start_tls @signature
    end