type os/exec.closeOnce

4 uses

	os/exec (current package)
		exec.go#L590: 	wc := &closeOnce{File: pw}
		exec.go#L595: type closeOnce struct {
		exec.go#L602: func (c *closeOnce) Close() error {
		exec.go#L607: func (c *closeOnce) close() {