DELIMITERS = "<$.>" ;

BEFORE-SECTIONS

SETPARENT (startfirst) TO (0** (first)) ;
SETPARENT (startsecond) TO (0** (second)) ;

SETPARENT (startthird) TO (0**W (third)) ;
SETPARENT (startfourth) TO (0**W (fourth)) ;

ADD (@self) (startfirst) (0*S (startfirst)) ;
ADD (@neighbour-left) (startsecond) (0*S (startfirst)) ;
ADD (@neighbour-right) (startfourth) (0*S (startfirst)) ;

ADD (@error-not-first) (startthird) (NOT 0* (startfirst)) ;
