How to get a value, from bucket, using the REST API

Can someone provide an example, of how someone using a REST tool, for example Rest console, of postman, could retrieve a value stored in a bucket, by providing key,bucket credentials,or/and server credentials?
thanks in advance

The REST API in Couchbase Server is generally used to manage clusters, server nodes, and buckets, and to retrieve run-time statistics within your Couchbase Server deployment.

Data operations, such as set and get for example, are best handled by Couchbase SDKs. (Check out to download Couchbase SDK in the language of your choice).