code: @Pure
  	protected int compareSegments(ST s1, ST s2) {
  		assert s1 != null && s2 != null;
  		return s1.hashCode() - s2.hashCode();
  	}
docs: Compare the two given segments.
  
  @param s1 the first segment.
  @param s2 the second segment.
  @return <code>-1</code> if {@code s1} is lower than {@code s2},
  <code>1</code> if {@code s1} is greater than {@code s2},
  otherwise <code>0</code>.