docs: function getStats(results, done) {
    const databases = results.databases;
  
    const keys = ['document_count', 'storage_size', 'index_count', 'index_size'];
    const stats = {};
    keys.map(function(k) {
      stats[k] = 0;
    });
    databases.map(function(db) {
      keys.map(function(k) {
        stats[k] += db[k];
      });
    });
    done(null, stats);
  }