@NotNull
  protected static PySequenceExpression unwrapCollection(@NotNull PsiElement literal) {
    final PyParenthesizedExpression parenthesizedExpression = as(literal, PyParenthesizedExpression.class);
    if (parenthesizedExpression != null) {
      final PyExpression containedExpression = parenthesizedExpression.getContainedExpression();
      assert containedExpression != null;
      return (PyTupleExpression)containedExpression;
    }
    return (PySequenceExpression)literal;
  }
@NotNull
  protected static PySequenceExpression unwrapCollection(@NotNull PsiElement literal)