code: function addTodo(text) {
      var todo = {
        _id: new Date().toISOString(),
        title: text,
        completed: false
      };
      db.put(todo, function callback (err, result) {
        if (!err) {
          console.log('Successfully posted a todo!');
        }
      });
    }
docs: We have to create a new todo document and enter it in the database