/// <summary>
/// Parses the <c>xsd:boolean</c> value of the indicated attribute, returning <c>true</c> for
/// a value of <c>"true"</c> or <c>"1"</c>, <c>false</c> for a value of <c>"false"</c> or
/// <c>"0"</c>, or <c>null</c> if the attribute does not exist. If the attribute exists but
/// does not match any of the above values, an exception is thrown.
/// </summary>
/// <param name="element"></param>
/// <param name="attributeName"></param>
/// <returns></returns>
/// <exception cref="FormatException">
/// The attribute is present but not a valid <c>xsd:boolean</c> value ( <c>"0"</c>,
/// <c>"false"</c>, <c>"1"</c>, or <c>"true"</c>).
/// </exception>
public static bool?ParseXsdBooleanAttribute(IXPathNavigable element, XName attributeName)
{
Checker.NotNull(element, "element");
Checker.NotNull(attributeName, "attributeName");
var attributeValue = element.AttributeValue(attributeName);
return(ParseXsdBooleanAttributeValue(attributeName, attributeValue));
}