code: def validateMasterOption(master):
      
      try:
          hostname, port = master.split(":")
          port = int(port)
      except (TypeError, ValueError):
          raise usage.UsageError("master must have the form 'hostname:port'")
docs: Validate master (-m, --master) command line option.
  
      Checks that option is a string of the 'hostname:port' form, otherwise
      raises an UsageError exception.
  
      @type  master: string
      @param master: master option
  
      @raise usage.UsageError: on invalid master option