TrySetDefault.cs

private IDisposable TrySetDefaultBindMode(XamlObjectDefinition xamlObjectDefinition)
{
    var definedMode = xamlObjectDefinition.Members.FirstOrDefault(m => m.Member.Name == "DefaultBindMode")?.Value?.ToString();

    if (definedMode == null)
    {
        return null;
    }
    else if (!IsValid(definedMode))
    {
        throw new InvalidOperationException(
            "Invalid value specified for attribute 'DefaultBindMode'.  Accepted values are 'OneWay', 'OneTime', or 'TwoWay'.");
    }
    else
    {
        _currentDefaultBindMode.Push(definedMode);
        return new DisposableAction(() => _currentDefaultBindMode.Pop());
    }

    bool IsValid(string mode)
    {
        switch (mode)
        {
            case "OneWay":
            case "OneTime":
            case "TwoWay":
                return true;
            default:
                return false;
        }
    }
}