code: def apply_dependencies(self):
          
          for host in self:
              for parent_id in getattr(host, 'parents', []):
                  if parent_id is None:
                      continue
                  parent = self[parent_id]
                  if parent.active_checks_enabled:
                      # Add parent in the list
                      host.act_depend_of.append((parent_id, ['d', 'x', 's', 'f'], '', True))
  
                      # Add child in the parent
                      parent.act_depend_of_me.append((host.uuid, ['d', 'x', 's', 'f'], '', True))
  
                      # And add the parent/child dep filling too, for broking
                      parent.child_dependencies.add(host.uuid)
                      host.parent_dependencies.add(parent_id)
docs: Loop on hosts and register dependency between parent and son
  
          call Host.fill_parents_dependency()
  
          :return: None