code: void insertValueAtPosition(final long value, final int pos) {
      if ((pos < 0) || (pos >= getNumSamples())) {
        throw new SketchesArgumentException("Insert position must be between 0 and " + getNumSamples()
            + ", inclusive. Received: " + pos);
      }
  
      data_[pos] = value;
    }
docs: Useful during union operation to force-insert a value into the union gadget. Does <em>NOT</em>
  increment count of items seen. Cannot insert beyond current number of samples; if reservoir is
  not full, use update().
  
  @param value The entry to store in the reservoir
  @param pos The position at which to store the entry