code: function(s1, s2)
  {
     var rval = 0;
     
     if(s1.length == s2.length)
     {
        rval = _compare(s1, s2);
     }
     else if(s1.length > s2.length)
     {
        rval = _compare(s1.substr(0, s2.length), s2);
     }
     else
     {
        rval = _compare(s1, s2.substr(0, s1.length));
     }
     
     return rval;
  }
docs: Compares two serializations for the same blank node. If the two
  serializations aren't complete enough to determine if they are equal (or if
  they are actually equal), 0 is returned.
  
  @param s1 the first serialization.
  @param s2 the second serialization.
  
  @return -1 if s1 < s2, 0 if s1 == s2 (or indeterminate), 1 if s1 > v2.