const golang.org/x/sys/unix.LOCK_EX

2 uses

	golang.org/x/sys/unix (current package)
		zerrors_darwin_amd64.go#L892: 	LOCK_EX                           = 0x2

	github.com/go-git/go-billy/v5/osfs
		os_posix.go#L15: 	return unix.Flock(int(f.File.Fd()), unix.LOCK_EX)