if n.Bytes == nil {
		return false
	}
	_, l := n.ReadVarint(1)
	return l == 1 && *n.Data(2) == '_'
}

// writeVarint writes n to buf in varint form. Returns the
// number of bytes written. n must be nonnegative.
// Writes at most 10 bytes.
func writeVarint(buf []byte, n int) int {
	for i := 0; ; i++ {
		b := byte(n & 0x7f)
		n >>= 7
		if n == 0 {
			buf[i] = b
			return i + 1
		}