docs: def get_reference(self, rtype: str, label: str):
          """ Return reference filed under rtype/label
  
           The references are organized by field/label, e.g. category/cat1.
           This lets us use a shorthand notation to go the resource, e.g.
           ref:category:cat1 instead of folder1/folder2/cat1.
           """
  
          # We are doing this instead of dictionary access in case we change
          # the storage later to a multidict thingy for optimization.
  
          reftype = self.data.get(rtype)
          if reftype:
              # The reftype might be "python" or "sphinx" or something else
              # from an Intersphinx registry, not something internal to
              # Kaybee.
              return reftype[label]