Couchbase group by data

Couchbase Server
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I know the couchbase map/reduce can be used to group by using group_level but I want group the data and not just want the count.Here is the scenario

Here is the data in couchbase

{"key":"key1","value":"value1"}
 {"key":"key2","value":"value2"}
 {"key":"key1","value":"value3"}

Now I want, is

{key:"key1","value":[value1,value3]}
{key:"key2","value":[value2]}

Is there a way I can achieve this thru map/reduce functionality in couchbase?