code: def main():
      
      shell = Shell()
  
      print(shell.terminal_type())
  
      r = shell.execute('pwd')  # copy line replace
      print(r)
  
      # shell.list()
  
      # print json.dumps(shell.command, indent=4)
  
      # test some commands without args
      """
      for cmd in ['whoami', 'pwd']:
          r = shell._execute(cmd)
          print ("---------------------")
          print ("Command: {:}".format(cmd))
          print ("{:}".format(r))
          print ("---------------------")
      """
      r = shell.execute('ls', ["-l", "-a"])
      print(r)
  
      r = shell.execute('ls', "-l -a")
      print(r)
  
      r = shell.ls("-aux")
      print(r)
  
      r = shell.ls("-a", "-u", "-x")
      print(r)
  
      r = shell.pwd()
      print(r)
docs: a test that should actually be added into a nosetest
      :return: