code: function setaVal(obj, k, v) {
    if (obj.hasOwnProperty(k)) {
      var val = obj[k];
      if (!_.isArray(val)) { obj[k] = [val]; }
      obj[k].push(v);
    }
    else { obj[k] = v; }
  }
docs: set prop k to v - convert to array and push if obj[k] exists