code: public Vector slice(int from, int until) {
          if (until - from < 0) {
              fail("Wrong slice range: [" + from + ".." + until + "].");
          }
  
          Vector result = blankOfLength(until - from);
  
          for (int i = from; i < until; i++) {
              result.set(i - from, get(i));
          }
  
          return result;
      }
docs: Retrieves the specified sub-vector of this vector. The sub-vector is specified by
  interval of indices.
  
  @param from the beginning of indices interval
  @param until the ending of indices interval
  
  @return the sub-vector of this vector