public ISpatialIndex BuildIndex(IQueryable<ISpatialDocument> documents)
        {
            var index = new LinearSpatialIndex();

            foreach (var doc in documents)
            {
                index.Add(doc);
            }

            return index;
        }
        public ISpatialIndex BuildIndex(IQueryable <ISpatialDocument> documents)
        {
            var index = new LinearSpatialIndex();

            foreach (var doc in documents)
            {
                index.Add(doc);
            }

            return(index);
        }