code: def add_links(self, parent, children):
          
          new_sensors = []
          if parent not in self:
              self._add_sensor(parent)
              new_sensors.append(parent)
          for child in children:
              if child not in self:
                  self._add_sensor(child)
                  new_sensors.append(child)
              self._parent_to_children[parent].add(child)
              self._child_to_parents[child].add(parent)
  
          self.recalculate(parent, children)
          for sensor in new_sensors:
              sensor.attach(self)
docs: Create dependency links from parent to child.
  
          Any sensors not in the tree are added. After all dependency links have
          been created, the parent is recalculated and the tree attaches to any
          sensors it was not yet attached to. Links that already exist are
          ignored.
  
          Parameters
          ----------
          parent : :class:`katcp.Sensor` object
              The sensor that depends on children.
          children : sequence of :class:`katcp.Sensor` objects
              The sensors parent depends on.