metrics.json

{
   "metrics":[
      {
         "id":"all",
         "segment":null
      },
      {
         "id":"push_enabled",
         "segment":{
            "operator":"and",
            "expressions":[
               {
                  "field":"push_token",
                  "comparer":"!=",
                  "value":null
               },
               {
                  "field":"opt_out",
                  "comparer":"!=",
                  "value":true
               }
            ]
         }
      }
   ]
}