编写一段Python代码，将一个字符串转换为标题字母（单词首字母大写）
string = "the quick brown fox jumps over the lazy dog."
下面是一个可能的Python代码实现：

```python
string = "the quick brown fox jumps over the lazy dog."
title_string = string.title()
print(title_string)
```

输出为：

```python
The Quick Brown Fox Jumps Over The Lazy Dog.
```