code: public Seq<T> slice(final int fromIndex, final int toIndex) {
          N.checkFromToIndex(fromIndex, toIndex, size());
  
          if (N.isNullOrEmpty(coll)) {
              return this;
          }
  
          if (coll instanceof List) {
              return new Seq<T>(((List<T>) coll).subList(fromIndex, toIndex));
          }
  
          return new Seq<T>(new SubCollection<>(coll, fromIndex, toIndex));
      }
docs: Returns a read-only <code>Seq</code>.
  
  @param fromIndex
  @param toIndex
  @return