View history of changes for a single line

• View history of changes for a single line in a file.
• Git blame of a single line, instead of the entire file.
• GitHub has this feature: https://help.github.com/articles/tracing-changes-in-a-file/
• As mentioned from Hacker News: https://news.ycombinator.com/reply?id=16651873&goto=item%3Fid%3D16649678%2316651873