add simple spinner/counter example

examples/counter/main.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"github.com/schollz/progressbar/v3"
+	"time"
+)
+
+// This example illustrates a simple spinner that displays the number of
+// received calls
+func main() {
+	bar := progressbar.NewOptions64(
+		-1,
+		progressbar.OptionSetDescription("[Counter Example] Received"),
+		progressbar.OptionSetWidth(10),
+		progressbar.OptionThrottle(65*time.Millisecond),
+		progressbar.OptionShowCount(),
+		progressbar.OptionSpinnerType(14),
+		progressbar.OptionFullWidth(),
+		progressbar.OptionSetRenderBlankState(true),
+	)
+
+	c := make(chan int)
+
+	go func(notify chan<- int) {
+		defer close(notify)
+		for i := 0; i < 100; i++ {
+			c <- i
+			time.Sleep(time.Millisecond * 100)
+		}
+	}(c)
+
+	for v := range c {
+		bar.Add(v)
+	}
+}