old_contents: from webapp_health_monitor.backends.system import FileSystemBackend
  from webapp_health_monitor.verificators.base import RangeVerificator
  
  
  class FreeDiskSpaceVerificator(RangeVerificator):
      mount_point = '/'
  
      def __init__(self, *args, **kwargs):
          super(FreeDiskSpaceVerificator, self).__init__(*args, **kwargs)
          self.backend = FileSystemBackend(self.mount_point)
  
      def get_value(self):
          return self.backend.free_space
  
  
  class PercentUsedDiskSpaceVerificator(RangeVerificator):
      mount_point = '/'
  
      def __init__(self, *args, **kwargs):
          super(PercentUsedDiskSpaceVerificator, self).__init__(*args, **kwargs)
          self.backend = FileSystemBackend(self.mount_point)
  
      def get_value(self):
          return self.backend.percent_used
  
new_contents: from webapp_health_monitor.backends.system import FileSystemBackend
  from webapp_health_monitor.verificators.base import RangeVerificator
  
  
  class FreeDiskSpaceVerificator(RangeVerificator):
      value_description = 'Free disk space'
      mount_point = '/'
  
      def __init__(self, *args, **kwargs):
          super(FreeDiskSpaceVerificator, self).__init__(*args, **kwargs)
          self.backend = FileSystemBackend(self.mount_point)
  
      def get_value(self):
          return self.backend.free_space
  
  
  class PercentUsedDiskSpaceVerificator(RangeVerificator):
      value_description = 'Percent disk used'
      mount_point = '/'
  
      def __init__(self, *args, **kwargs):
          super(PercentUsedDiskSpaceVerificator, self).__init__(*args, **kwargs)
          self.backend = FileSystemBackend(self.mount_point)
  
      def get_value(self):
          return self.backend.percent_used
  
subject: Add descriptions to system verificators.