code: def maintenance_center(self, storage_disk_xml=None):
          
  
          disk_in_maintenance = 0
  
          for filer_disk in storage_disk_xml:
              disk_status = filer_disk.find('disk-raid-info/container-type')
              if disk_status.text == 'maintenance':
                  disk_in_maintenance += 1
  
          self.push('maintenance_disk', 'disk', disk_in_maintenance)
docs: Collector for how many disk(s) are in NetApp maintenance center
  
              For more information on maintenance center please see:
                bit.ly/19G4ptr