/// <summary>
/// Establish a namespace context mapping from prefix to URI
/// that will be used in Comparison.Detail.XPath.
/// </summary>
/// <remarks>
/// Without a namespace context (or with an empty context) the
/// XPath expressions will only use local names for elements and
/// attributes.
/// </remarks>
public CompareConstraint WithNamespaceContext(IDictionary <string, string> ctx)
{
diffBuilder.WithNamespaceContext(ctx);
return(this);
}