feat: add lab7

Lab7/cs2030s/fp/Action.java

@@ -0,0 +1,18 @@
+package cs2030s.fp;
+
+/**
+ * Represent a function that acts on a value.
+ * CS2030S Lab 5
+ * AY22/23 Semester 1
+ *
+ * @param <T> The type of the input value.
+ */
+@FunctionalInterface
+interface Action<T> {
+  /**
+   * The functional method to act on the value t.
+   *
+   * @param t The input value.
+   */
+  void call(T t);
+}