clientv3/op.go
func OpGet(key string, opts ...OpOption) Op {
	// WithPrefix and WithFromKey are not supported together
	if isWithPrefix(opts) && isWithFromKey(opts) {
		panic("`WithPrefix` and `WithFromKey` cannot be set at the same time, choose one")
	}
	ret := Op{t: tRange, key: []byte(key)}
	ret.applyOpts(opts)
	return ret
}
func OpGet(key string, opts ...OpOption) Op {
	// WithPrefix and WithFromKey are not supported together
	if isWithPrefix(opts) && isWithFromKey(opts) {
		panic("`WithPrefix` and `WithFromKey` cannot be set at the same time, choose one")
	}
	ret := Op{t: tRange, key: []byte(key)}
	ret.applyOpts(opts)
	return ret
}
// OpGet returns "get" operation based on given key and operation options.