added example

example_multi_test.go

@@ -0,0 +1,21 @@
+package bps
+
+import (
+	"fmt"
+	"log"
+	"time"
+)
+
+func ExampleMulti() {
+	// Create a Multi that records information for 1s, 10s, and 1m
+	bw, err := NewMulti(1*time.Second, 10*time.Second, 1*time.Minute)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Add some data, then print out rates;w
+	bw.Add(1)
+	fmt.Printf("%v\n", len(bw.Rate()))
+	// Output:
+	// 3
+}