old_contents: #!/usr/bin/env python3
  
  from sys import argv
  from server import Server
  
  class Main:
    def __init__(self, url):
      self.server = Server(url)
  
    def run(self):
      self.server.connect();
      command = self.server.get()
      while command is not None:
        response = command.execute()
        self.server.send(response)
        command = self.server.get()
  
  main = Main(argv[1]);
  main.run()
new_contents: #!/usr/bin/env python3
  
  from server import Server
  import argparse
  
  class Main:
    def __init__(self, url):
      self.server = Server(url)
  
    def run(self):
      self.server.connect();
      command = self.server.get()
      while command is not None:
        response = command.execute()
        self.server.send(response)
        command = self.server.get()
  
  def parseCommandLine():
  	parser = argparse.ArgumentParser()
  	parser.add_argument("--url", required=True)
  	return parser.parse_args()
  
  args = parseCommandLine()
  main = Main(args.url);
  main.run()
subject: Add command line validation