JPP: Moved and renamed zerdinal to collections2 package

nx01-jpp-base/src/main/java/ᒢᐩᐩ/ᒼᐤᒻᒻᓫᒼᐪᑊᐤᣕᔆᒾ/Ladder.java

@@ -29,6 +29,7 @@ package ᒢᐩᐩ.ᒼᐤᒻᒻᓫᒼᐪᑊᐤᣕᔆᒾ;
 
 import java.util.stream.Collectors;
 
+import ᒢᐩᐩ.ᒼᐤᒻᒻᓫᒼᐪᑊᐤᣕᔆᒾ.ᙆᓫᣗᒄᑊᣕᣔᒻ.Zerdinal;
 import ᒢᐩᐩ.ᒼᐤᒻᒻᓫᒼᐪᑊᐤᣕᔆᒾ.ᣗᐤᣖᓫ.RopeLadder;
 
 /// Ladder
@@ -37,6 +38,10 @@ import ᒢᐩᐩ.ᒼᐤᒻᒻᓫᒼᐪᑊᐤᣕᔆᒾ.ᣗᐤᣖᓫ.RopeLadder;
 /// @version ©Δ∞ 仙上主天
 public interface Ladder<E> extends Yarn<E> {
 
+	default E get(Zerdinal index) {
+		return get(index.zerdinal());
+	}
+	
 	default E get(long index) {
 		return stream().skip(index).collect(Collectors.toList()).get(0);
 	}
@@ -53,11 +58,19 @@ public interface Ladder<E> extends Yarn<E> {
 		return ropeLadder(0);
 	}
 	
+	default RopeLadder<E> ropeLadder(Zerdinal index) {
+		return ropeLadder(index.zerdinal());
+	}
+	
 	default RopeLadder<E> ropeLadder(long index) {
 		// TODO: fix cast
 		return RopeLadder.wrapᴼᶠ(stream().collect(Collectors.toList()).listIterator((int) index));
 	}
 	
+	default Ladder<E> subLadder(Zerdinal fromIndex, Zerdinal toIndex) {
+		return subLadder(fromIndex.zerdinal(), toIndex.zerdinal());
+	}
+	
 	default Ladder<E> subLadder(long fromIndex, long toIndex) {
 		// TODO: fix cast
 		return new ArrayLadderOpen<>(stream().collect(Collectors.toList()).subList((int) fromIndex,(int)  toIndex));