You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: main.go
    path of file: ./repos/gopherjs/tests/testdata/legacy_syscall
    
    the code of the file until where you have to start completion: //go:build legacy_syscall && gopherjs
// +build legacy_syscall,gopherjs

// This program tests GopherJS's ability to perform raw syscalls using the
// deprecated node_syscall ex
    
func main() {
	msg := []byte("Hello, world!\n")
	_, _, errno := syscall.Syscall(1 /* SYS_WRITE on Linux */, 1 /* stdout */, uintptr(unsafe.Pointer(&msg[0])), uintptr(len(msg)))
	if errno != 0 {
		println(errno.Error())
	}
}