code: def docker_version(host=None, component='server'):
      
  
      if component.lower() == 'client':
          component = 'Client'
      else:
          component = 'Server'
  
      # sudo is required for non-coreOS installs
      command = 'sudo docker version -f {{.{}.Version}}'.format(component)
  
      if host is None:
          success, output = shakedown.run_command_on_master(command, None, None, False)
      else:
          success, output = shakedown.run_command_on_host(host, command, None, None, False)
  
      if success:
          return output
      else:
          return 'unknown'
docs: Return the version of Docker [Server]
  
          :param host: host or IP of the machine Docker is running on
          :type host: str
          :param component: Docker component
          :type component: str
          :return: Docker version
          :rtype: str