new_contents: from cmd3.shell import command
  from cloudmesh_common.logger import LOGGER
  import os
  from cloudmesh_common.tables import row_table
  
  log = LOGGER(__file__)
  
  
  class cm_shell_nova:
  
      """opt_example class"""
  
      def activate_cm_shell_nova(self):
          self.register_command_topic('cloud','nova')
          pass
  
      @command
      def do_nova(self, args, arguments):
          """
          Usage:
                 nova login
                 nova info               
                 nova help
                 nova ARGUMENTS               
  
          A simple wrapper for the openstack nova command
  
          Arguments:
  
            ARGUMENTS      The arguments passed to nova
            help           Prints the nova manual
            login          reads the information from the current cloud
                           and updates the environment variables if
                           the cloud is an openstack cloud
            info           the environment values for OS
            
          Options:
  
             -v       verbose mode
  
          """
          # log.info(arguments)
  
          if arguments["help"]:
              os.system("nova help")
              return
          elif arguments["info"]:
              #
              # prints the current os env variables for nova
              #
              d = {}
  
              for attribute in ['OS_USER_ID',
                                'OS_USERNAME',
                                'OS_TENANT_NAME',
                                'OS_AUTH_URL',
                                'OS_CACERT',
                                'OS_PASSWORD',
                                'OS_REGION']:
                  try:
                      d[attribute] = os.environ[attribute]
                  except:
                      d[attribute] = None
              print row_table(d, order=None, labels=["Variable", "Value"])
              return
          elif arguments["login"]:
              print "Not yet implemented"
              #
              # TODO: implemet
              #
              # cloud = get current default
              # if cloud type is openstack:
              #    credentials = get credentials 
              #    set the credentials in the current os system env variables
              #    
          else:
              os.system("nova {0}".format(arguments["ARGUMENTS"]))
              return
  
  
subject: add a nova command