docs: public boolean encloses(int regionOffset, int regionLength, int offset, boolean includeRegionEnd) {
  		if (offset < 0)
  			// TODO should this be "return false;" instead?
  			throw new IllegalArgumentException("offset may not be negative");
  		int relativeOffset = offset - regionOffset;
  		boolean result = relativeOffset == 0 || (relativeOffset > 0 && (includeRegionEnd ? relativeOffset <= regionLength : relativeOffset < regionLength));
  		return result;
  	}