update

src/main/java/rocks/zipcode/quiz3a/fundamentals/StringUtils.java

     public static Boolean isIsogram(String str) {
         return null;
     }
+
+    public static Boolean hasDuplicateCharacters(String str) {
+        return null;
+    }
+
+    public static String removeConsecutiveDuplicateCharacters(String str) {
+        return null;
+    }
 }

src/test/java/rocks/zipcode/quiz3a/fundamentals/calculator/SquareRootTest.java

+package rocks.zipcode.quiz3a.fundamentals.calculator;
+
+public class SquareRootTest {
+}

src/test/java/rocks/zipcode/quiz3a/fundamentals/stringutils/IsIsoGramTest.java

+package rocks.zipcode.quiz3a.fundamentals.stringutils;
+
+public class IsIsoGramTest {
+}