old_contents: from typing import Dict, Set
  import numpy
  
  from model import location
  
  class DTM:
  
      countries: location.Countries = {}
      data = None
  
new_contents: from typing import Dict, Set
  import numpy
  
  from model import location
  
  class DTM:
  
      countries: location.Countries = {}
      data = None
  
      def get_visuals(self):
          pass
subject: add get_visuals placeholder