         # File lib/em/connection.rb, line 293
    293:     def start_tls args={}
    294:       priv_key, cert_chain, verify_peer = args.values_at(:private_key_file, :cert_chain_file, :verify_peer)
    295:
    296:       [priv_key, cert_chain].each do |file|
    297:         next if file.nil? or file.empty?
    298:         raise FileNotFoundException,
    299:           "Could not find #{file} for start_tls" unless File.exists? file
    300:       end
    301:
    302:       EventMachine::set_tls_parms(@signature, priv_key || '', cert_chain || '', verify_peer)
    303:       EventMachine::start_tls @signature
    304:     end