code: def register_transform(self, node_class, transform, predicate=None):
          
          self.transforms[node_class].append((transform, predicate))
docs: Register `transform(node)` function to be applied on the given
          astroid's `node_class` if `predicate` is None or returns true
          when called with the node as argument.
  
          The transform function may return a value which is then used to
          substitute the original node in the tree.