get instruction type

[kuchaguangjie]

https://solana.stackexchange.com/questions/19331/best-way-to-find-the-transferchecked-and-transfer-instruction-from-a-tx
Here in the comment, it says the first byte of instruction data is instruction type.

rust code is here:
https://github.com/solana-program/token/blob/8fe3789d1dc3fdf849886e4c5a0db7bebaa86f63/program/src/instruction.rs#L506

Can you add a method to get instruction type from the instruction ?

I tried, with this but seems not correct:

func GetInstType(inst *solana.CompiledInstruction) int {
	if len(inst.Data) == 0 {
		return 0
	}
	return int(inst.Data[0])
}