System.IO.Packaging.PackUriHelper.GetSourcePartUriFromRelationshipPartUri C# (CSharp) Method

        public static Uri GetSourcePartUriFromRelationshipPartUri(Uri relationshipPartUri)
        {
            //Check.RelationshipPartUri (relationshipPartUri);
            if (!IsRelationshipPartUri(relationshipPartUri))
                throw new Exception("is not a relationship part!?");
            return null;
        }