Draw a walk's rows and variants through pathDraws, off the pin set and the walk's signature

template.go

@@ -273,11 +273,11 @@ func fieldTokens(format string) []string {
 // tail is what makes the arm a bound draw: its head is drawn once per expansion
 // (see compileOps).
 type arm struct {
-	name  string // as written, for messages
-	key   string
-	tail  []string
-	steps []string // key per level passed through; the head and leaf hold their own
-	path  string   // key and tail, the one spelling every way of writing this read shares
+	name   string // as written, for messages
+	key    string
+	tail   []string
+	levels []string // the key at each level the tail passes through, the head's first
+	path   string   // key and tail, the one spelling every way of writing this read shares
 }
 
 // splitArm splits one name into key and tail. refs maps a reference to what
@@ -302,11 +302,11 @@ func splitArm(name string, refs map[string]refBinding) arm {
 }
 
 func pathArm(name, key string, segs []string) arm {
-	var steps []string
-	for i := 0; i < len(segs)-1; i++ { // every level except the leaf's own
-		steps = append(steps, key+"."+strings.Join(segs[:i+1], "."))
+	levels := []string{key}
+	for i := 0; i < len(segs)-1; i++ {
+		levels = append(levels, key+"."+strings.Join(segs[:i+1], "."))
 	}
-	return arm{name: name, key: key, tail: segs, steps: steps, path: key + "." + strings.Join(segs, ".")}
+	return arm{name: name, key: key, tail: segs, levels: levels, path: key + "." + strings.Join(segs, ".")}
 }
 
 // splitArms splits a token body's '|' alternatives.