code: function find (state, prefix, objectsOrIds) {
    return Array.isArray(objectsOrIds)
      ? findMany(state, objectsOrIds, prefix)
      : findOne(state, objectsOrIds, prefix)
  }
docs: finds existing object in local database
  
  @param  {String}                 prefix        optional id prefix
  @param  {String|Object|Object[]} objectsOrIds  Id of object or object with
  `._id` property
  @return {Promise}