code: def _traverse_child_objs(self, goobj_parent):
          
          parent_id = goobj_parent.id
          # mark parent as seen
          self.seen_pids.add(parent_id)
          self.godag.go2obj[parent_id] = goobj_parent
          # Loop through children
          for child_obj in goobj_parent.children:
              child_id = child_obj.id
              self.godag.p2cs[parent_id].add(child_id)
              # If child has not been seen
              if child_id not in self.seen_pids:
                  self._traverse_child_objs(child_obj)
docs: Traverse from source GO down children.