@Nullable
  private static PySkeletonHeader readSkeletonHeader(@NotNull VirtualFile file, @NotNull Sdk pythonSdk) {
    final VirtualFile skeletonsDir = findSkeletonsDir(pythonSdk);
    if (skeletonsDir != null && VfsUtilCore.isAncestor(skeletonsDir, file, false)) {
      PySkeletonHeader skeletonHeader = file.getUserData(CACHED_SKELETON_HEADER);
      if (skeletonHeader == null) {
        skeletonHeader = PySkeletonHeader.readSkeletonHeader(VfsUtilCore.virtualToIoFile(file));
        file.putUserData(CACHED_SKELETON_HEADER, skeletonHeader);
      }
      return skeletonHeader;
    }
    return null;
  }
@Nullable
  private static PySkeletonHeader readSkeletonHeader(@NotNull VirtualFile file, @NotNull Sdk pythonSdk)