/// <summary>
/// Returns the <see cref="OpenXmlPart" />'s root element <see cref="XNamespace" />.
/// </summary>
/// <param name="part">The part.</param>
/// <returns>The namespace.</returns>
public static XNamespace GetRootNamespace(this OpenXmlPart part)
{
if (part == null)
{
throw new ArgumentNullException("part");
}
var root = part.GetRootElement();
return(root != null ? root.Name.Namespace : null);
}