// P_Mod(path, count, count)
// One step.
Iterator<Node> iter = eval(pathStep, node) ;
// Build a path for all remaining steps.
long count2 = dec(fixedLength) ;
P_FixedLength nextPath = new P_FixedLength(pathStep, count2) ;
// For each element in the first step, do remaining step
// Accumulate across everything from first step.
for (; iter.hasNext();) {
Node n2 = iter.next() ;
Iterator<Node> iter2 = eval(nextPath, n2) ;