### Question:
Rope { public Rope slice(int start, int end) { if (start < this.start || end > this.start + this.length) { throw new IllegalArgumentException( "[" + start + ", " + end + ") interval is out of bounds for current rope"); } Node root = this.root; start += this.start; end += this.start - 1; while (root.getHeight() > 0) { ChildIndexOffset indexOffset = getChildIndexOffset(root.getChildren(), start, end); if (indexOffset != null) { int index = indexOffset.index; int offset = indexOffset.offset; root = root.getChildren().get(index); start -= offset; end -= offset; } else { break; } } return Rope.from(root.getString().substring(start, end - start + 1)); } private  Rope(Node root, int start, int length); static Rope from(String s); int length(); Rope slice(int start, int end); Rope replace(int start, int end, String newString); Rope concat(Rope anotherRope); @Override String toString(); @Override boolean equals(Object obj); @Override int hashCode();  }### Answer:
@Test public void testSlice() { Rope a = Rope.from("hello world"); Rope b = a.slice(1, 9); assertEquals(b.toString(), "ello wo"); assertNotEquals(a, b); Rope readme = Rope.from(text); Rope title = readme.slice(0, 4); assertEquals(title.toString(), "Rope"); assertNotEquals(title, readme); }