the semaphore.
This is a common idiom for limiting concurrency.
</p>

<p>
This program starts a goroutine for every entry in the work list, but the
goroutines coordinate using the <code>limit</code> channel to ensure
that at most three are running work functions at a time.
</p>

<pre>
var limit = make(chan int, 3)

func main() {
	for _, w := range work {

f := func() int { return 7 }
ch := make(chan int)
r, w, _ := os.Pipe()  // os.Pipe() returns a connected pair of Files and an error, if any
_, y, _ := coord(p)   // coord() returns three values; only interested in y coordinate
</pre>

<p>
Unlike regular variable declarations, a short variable declaration may <i>redeclare</i>
variables provided they were originally declared earlier in the same block

f := func() int { return 7 }
ch := make(chan int)
r, w, _ := os.Pipe()  // os.Pipe() returns a connected pair of Files and an error, if any
_, y, _ := coord(p)   // coord() returns three values; only interested in y coordinate
</pre>

<p>
Unlike regular variable declarations, a short variable declaration may <i>redeclare</i>
variables provided they were originally declared earlier in the same block