I can get the element which attribute contains `X` but I can't get the attribute itself. Why?

This code does not raise any errors:

```
links = browser.find_elements_by_xpath('//div[@aria-label="Conversations"]//a[contains(@data-href, "https://www.messenger.com/t/")]')

```

This code raises `NoSuchElementException` error:

```
links = browser.find_elements_by_xpath('//div[@aria-label="Conversations"]//a[contains(@data-href, "https://www.messenger.com/t/")]/@data-href')

```

This code is extracted from Messenger main page with the chats. I would like to get all links in the `ul` list...
I don't get it... Any help please?