func (c Client) SETNX(key string, value Value) (ok bool, err error) {
	return c.SET(key, value, IfNotExists)
}
SETNX is equivalent to SET(key, value, Flags{IfNotExists})

Works similar to https://redis.io/commands/setnx
package redimo
import (
	"context"
	"strings"
	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/service/dynamodb"
)
const emptySK = "/"
func (c Client) GET(key string) (val ReturnValue, err error) {
	resp, err := c.ddbClient.GetItemRequest(&dynamodb.GetItemInput{
		ConsistentRead: aws.Bool(c.consistentReads),
		Key:            keyDef{pk: key, sk: emptySK}.toAV(c),
		TableName:      aws.String(c.table),
	}).Send(context.TODO())
	if err != nil || len(resp.Item) == 0 {
		return
	}
	val = ReturnValue{resp.Item[vk]}
	return
}
func (c Client) SET(key string, value Value, flag Flag) (ok bool, err error) {
	builder := newExpresionBuilder()
	builder.updateSET(vk, value)
	if flag == IfNotExists {
		builder.addConditionNotExists(c.pk)
	}
	if flag == IfAlreadyExists {
		builder.addConditionExists(c.pk)
	}
	_, err = c.ddbClient.UpdateItemRequest(&dynamodb.UpdateItemInput{
		ConditionExpression:       builder.conditionExpression(),
		ExpressionAttributeNames:  builder.expressionAttributeNames(),
		ExpressionAttributeValues: builder.expressionAttributeValues(),
		UpdateExpression:          builder.updateExpression(),
		Key: keyDef{
			pk: key,
			sk: emptySK,
		}.toAV(c),
		TableName: aws.String(c.table),
	}).Send(context.TODO())
	if conditionFailureError(err) {
		return false, nil
	}
	if err != nil {
		return
	}
	return true, nil
}