-#alt2 txt = new RopeString.from(str)
-#alt2 trimable = new RopeString.from(spaces)
-#alt2 trimable = trimable + str
-#alt2 trimable = trimable + spaces
-#alt2 num = new RopeString.from(numstr)
+#alt3 txt = new RopeBuffer.from(str)
+#alt3 trimable = new RopeBuffer.from(spaces)
+#alt3 trimable.append(str)
+#alt3 trimable.append(spaces)
+#alt3 num = new RopeBuffer.from(numstr)