def retrieve_data(key = '')
      key = key.to_s unless key.is_a? String
      data_array = @db.execute 'SELECT value FROM data WHERE key = ?', key
      Marshal.load(data_array[0][0]) unless data_array[0].nil?
    end
def retrieve_data(key = '')
      key = key.to_s unless key.is_a? String
      data_array = @db.execute 'SELECT value FROM data WHERE key = ?', key
      Marshal.load(data_array[0][0]) unless data_array[0].nil?
    end
Retrieve whatever data is stored in at `key`, and return it!