public @Nullable PyTupleType asTupleType(@NotNull PsiElement anchor) {
    if (isUnbound()) {
      return PyTupleType.createHomogeneous(anchor, getElementTypes().get(0));
    }
    else {
      return PyTupleType.create(anchor, getElementTypes());
    }
  }
public @Nullable PyTupleType asTupleType(@NotNull PsiElement anchor)