code: func VarIntLen(i uint64) protocol.ByteCount {
  	if i <= maxVarInt1 {
  		return 1
  	}
  	if i <= maxVarInt2 {
  		return 2
  	}
  	if i <= maxVarInt4 {
  		return 4
  	}
  	if i <= maxVarInt8 {
  		return 8
  	}
  	panic(fmt.Sprintf("%#x doesn't fit into 62 bits", i))
  }
docs: // VarIntLen determines the number of bytes that will be needed to write a number