Xtop highest

.subckt highest 
* Node 7 ends here
X4 7 higher
RD 7 7 12k
.ends

.subckt higher h h2
X3 h medium
RH h h 12k
.ends

.subckt medium m
X2 m low
RM m m 12k
.ends

.subckt low L
X1 L lowest
RL L L 12k
.ends

.subckt lowest LL
RLL LL LL 12k
.ends

