verbose = flag.Bool("verbose", false, "verbose")
)

var wg sync.WaitGroup        // outstanding fetches
var urlq = make(chan string) // URLs to crawl

// urlFrag is a URL and its optional #fragment (without the #)
type urlFrag struct {
	url, frag string
}

var (
	mu          sync.Mutex
	crawled     = make(map[string]bool)      // URL without fragment -> true

}

var (
	D        MultiFlag
	I        MultiFlag
	PrintOut int
	DebugV   bool
)

func init() {
	flag.Var(&D, "D", "predefined symbol with optional simple value -D=identifier=value; can be set multiple times")
	flag.Var(&I, "I", "include directory; can be set multiple times")
	flag.BoolVar(&DebugV, "v", false, "print debug output")

The same assembler is used for all target operating systems and architectures.
The GOOS and GOARCH environment variables set the desired target.

Flags:

	-D name[=value]
		Predefine symbol name with an optional simple value.
		Can be repeated to define multiple symbols.
	-I dir1 -I dir2
		Search for #include files in dir1, dir2, etc,
		after consulting $GOROOT/pkg/$GOOS_$GOARCH.
	-S
		Print assembly and machine code.
	-V

// Addr2line is a minimal simulation of the GNU addr2line tool,
// just enough to support pprof.
//
// Usage:
//
//	go tool addr2line binary
//
// Addr2line reads hexadecimal addresses, one per line and with optional 0x prefix,
// from standard input. For each input address, addr2line prints two output lines,
// first the name of the function containing the address and second the file:line
// of the source code corresponding to that address.