a rule will simply 
  redefine it. The old definition is destructed. This follows more closely C++ 
  semantics and is more in line with what the user expects the rule to behave.</p>
<p><img src="theme/lens.gif" width="15" height="16"> <b>Sequencing Syntax</b> 
  <br>
  <br>
  The comma operator as in a, b seems to be a better candidate, syntax-wise. But 
  then the problem is with its precedence. It has the lowest precedence in C/C++, 
  which makes it virtually useless. <br>
  <br>
  Bjarne Stroustrup, in