Initial commit

src/main/java/com/example/util/AddFunction.java

@@ -0,0 +1,12 @@
+package com.example.util;
+
+public class AddFunction implements CalcFunction {
+
+    public double calc(double... input) {
+        double sum = 0;
+        for (double i : input) {
+            sum += i;
+        }
+        return sum;
+    }
+}

src/main/java/com/example/util/CalcFunction.java

@@ -0,0 +1,6 @@
+package com.example.util;
+
+public interface CalcFunction {
+
+    double calc(double... input);
+}