Google “Onebox” is a special Google search result shows results from its code search engine when you perform programming related search like, function names, classes, objects, methods so you can see real-life examples of use. For some reason, the snippets are always displayed after the third search result and they include up to four lines of code.
Google Code Search indexes "publicly accessible source code hosted on the Internet" and is the only search engine developed by Google that supports regular expressions and case-sensitive searches. It's also the only Google search engine that has keyboard shortcuts: after clicking on a search result, type n and p to go to the next/previous match.
Google, Search, Code Search, Search Result