Applying async/await feature to ArcGIS API for JavaScript code?

Question

How do I apply the async/await feature to this code? I need to wait for the reltionshipQuery and forEach to finish before I return contentSpecies.

        contentSpecies = function(value, key, data) {
          var contentSpecies = [];

            objectID = data.OBJECTID;

            var queryTask = new QueryTask({
                url: "https://webmaps.com/MapServer/1"
            });

            var relationQuery = new RelationshipQuery({
                objectIds: [objectID],
                outFields: ["Species", "Notes", "Status"],
                returnGeometry: true,
                relationshipId: 0
            });

            queryTask.executeRelationshipQuery(relationQuery)
            .then(function(rslts) {
                var features = rslts[objectID].features;
                features.forEach(function(ftr) {
                    var t = ftr.attributes;
                    var species = t.Species;
                    contentSpecies += "<span class='bold' title='Species'><b>Species: </b></span>" + species + "<br/>";
                    var notes = t.Notes;
                    contentSpecies += "<span class='bold' title='Notese'><b>Notes: </b></span>" + notes + "<br/>";
                    var status = t.Status;
                    contentSpecies += "<span class='bold' title='Status'><b>Status: </b></span>" + status + "<br/>";

                });

                //return contentSpecies;
            })
            return contentSpecies
        }

Answer 1

contentSpecies = async function(value, key, data) {
  try {
    ...
    let rslts = await queryTask.executeRelationshipQuery(relationQuery);
    var features = rslts[objectID].features;
    features.forEach(function(ftr) {
    ...
  } catch(e) {
    console.error(e);
  }
}

Answer 2

async function xxx(){    

 var results = await queryTask.executeRelationshipQuery(relationQuery)


}

It works for me - see Using async await in ArcGIS JavaScript API