@NotNull
  public static List<QualifiedName> findImportableQNames(@NotNull PsiElement foothold, @NotNull VirtualFile vfile) {
    final PythonPathCache cache = ResolveImportUtil.getPathCache(foothold);
    final List<QualifiedName> names = cache != null ? cache.getNames(vfile) : null;
    if (names != null) {
      return names;
    }
    PathChoosingVisitor visitor = new PathChoosingVisitor(vfile);
    RootVisitorHost.visitRoots(foothold, visitor);
    final List<QualifiedName> results = visitor.getResults();
    if (cache != null) {
      cache.putNames(vfile, results);
    }
    return results;
  }
@NotNull
  public static List<QualifiedName> findImportableQNames(@NotNull PsiElement foothold, @NotNull VirtualFile vfile)