feat(buffer): Added a buffer func for data sinks

buffer.go

@@ -0,0 +1,14 @@
+package pipeline
+
+// Buffer creates a buffered channel that will close after the input
+// is closed and the buffer is fully drained
+func Buffer(size int, in <-chan interface{}) <-chan interface{} {
+	buffer := make(chan interface{}, size)
+	go func() {
+		for i := range in {
+			buffer <- i
+		}
+		close(buffer)
+	}()
+	return buffer
+}