code: def dereference(self):
          
          all = []
          indexes = {}
          for child in self.children:
              child.content(all)
          dependencies = {}
          for x in all:
              x.qualify()
              midx, deps = x.dependencies()
              dependencies[x] = deps
              indexes[x] = midx
          for x, deps in dependency_sort(dependencies):
              midx = indexes.get(x)
              if midx is None:
                  continue
              d = deps[midx]
              log.debug("(%s) merging %s <== %s", self.tns[1], Repr(x), Repr(d))
              x.merge(d)
docs: Instruct all children to perform dereferencing.