关于打印素数的程序逻辑看不懂，谁能帮忙分析一下执行过程

// Copyright 2009 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file.package main package main import "fmt" // Send the sequence 2, 3, 4, ... to channel 'ch'. func generate(ch chan int) { for i := 2; ; i++ { ch <- i // Send 'i' to channel 'ch'. } } // Copy the values from channel 'in' to channel 'out', // removing those divisible by 'prime'. func filter(in, out chan int, prime int) { for { i := <-in // Receive value of new variable 'i' from 'in'. if i%prime != 0 { out <- i // Send 'i' to channel 'out'. } } } // The prime sieve: Daisy-chain filter processes together. func main() { ch := make(chan int) // Create a new channel. go generate(ch) // Start generate() as a goroutine. for { prime := <-ch fmt.Print(prime, " ") ch1 := make(chan int) go filter(ch, ch1, prime) ch = ch1 } }