code: function forEachNestedDependency(node, handler, key, parentNode) {
    if (isObject(node)) {
      if (isRootNode(node, key)) {
        stepInto(node.dependencies, handler);
      } else if (isPackage(node, key)) {
        handler(key, node, parentNode);
        stepInto(node, handler);
      } else if (isDependencyMap(node, key)) {
        stepInto(node, handler);
      }
    }
  }
docs: implementation