System.IO.Packaging.Check.Id C# (CSharp) Method

        public static void Id(object id)
        {
            NotNull(id, "id");
        }

        public void DeleteRelationship(string id)
        {
            Check.Id(id);
            CheckIsReadOnly();

            Relationships.Remove(id);

            relationshipsCollection.Relationships.RemoveAll(r => r.Id == id);
            if (Relationships.Count > 0)
            {
                using (Stream s = GetPart(RelationshipUri).GetStream())
                    WriteRelationships(relationships, s);
            }
            else
            {
                DeletePart(RelationshipUri);
            }
        }