lean into examples

examples/closures/closures.go

@@ -0,0 +1,20 @@
+package main
+
+import "fmt"
+
+func makeEvenGenerator() func() uint {
+    i := uint(0)
+    return func() uint {
+        i += 2
+        return i
+    }
+}
+
+func main() {
+    nextEven := makeEvenGenerator()
+    fmt.Println(nextEven())
+    fmt.Println(nextEven())
+    fmt.Println(nextEven())
+}
+
+// todo: note example of first-class functions.