Error while tying to run webrick, doesn't matter what port I specify I still get the same error

comand line prompt

$ ./myserver.rb
[2017-09-12 16:39:30] INFO  WEBrick 1.3.1
[2017-09-12 16:39:30] INFO  ruby 2.0.0 (2015-12-16) [universal.x86_64-darwin16]
[2017-09-12 16:39:30] WARN  TCPServer Error: Address already in use - bind(2)
[2017-09-12 16:39:30] INFO  WEBrick::GenericServer#start: pid=30434 port=3321
# on shutdown 
^C[2017-09-12 16:40:38] INFO  going to shutdown ...
[2017-09-12 16:40:38] INFO  WEBrick::GenericServer#start done.

#any lsof | grep 3321 returns no results

myserver.rb

#!/usr/bin/ruby
require 'webrick'

server = WEBrick::GenericServer.new Port: 3321 

trap('INT') { server.shutdown }

server.start do |socket|
  socket.puts Time.now
end

The Ruby code is verbatim what is in Beginning Ruby.