docs: def vdi_list(call=None, kwargs=None):
      '''
      Return available Xen VDI images
  
      If this function is called with the ``-f`` or ``--function`` then
      it can return a list with minimal deatil using the ``terse=True`` keyword
      argument.
  
      .. code-block:: bash
  
          salt-cloud -f vdi_list myxen terse=True
  
      '''
      if call == 'action':
          raise SaltCloudException(
              'This function must be called with -f or --function.')
      log.debug('kwargs is %s', kwargs)
      if kwargs is not None:
          if 'terse' in kwargs:
              if kwargs['terse'] == 'True':
                  terse = True
              else:
                  terse = False
          else:
              terse = False
      else:
          kwargs = {}
          terse = False
      session = _get_session()
      vdis = session.xenapi.VDI.get_all()
      ret = {}
      for vdi in vdis:
          data = session.xenapi.VDI.get_record(vdi)
          log.debug(type(terse))
          if terse is True:
              ret[data.get('name_label')] = {
                  'uuid': data.get('uuid'),
                  'OpqueRef': vdi}
          else:
              data.update({'OpaqueRef': vdi})
              ret[data.get('name_label')] = data
      return ret