code: private void addPossibleSignature(String name, Node node, NodeTraversal t) {
      if (node.isFunction()) {
        // The node we're looking at is a function, so we can add it directly
        addSignature(name, node, t.getSourceName());
      } else {
        nonMethodProperties.add(name);
      }
    }
docs: Adds a node that may represent a function signature (if it's a function
  itself or the name of a function).