I remember back in the there was code.google.com (or something like that) which allowed searching over repositories. I was assigned to creating firefox addon including native part with C++ and it was kind of daunting task, there were little documentation. This tool was indispensable for me, it allowed to quickly look at any API usage. I wouldn't be able to complete that project without it.

Since Google closed this project, I never used anything similar, but I think that I should be. I tried few times to use ordinary Github search, but it wasn't good enough to be useful. Hopefully this project will change it. Done properly it would be a very powerful tool.

What's not clear to me is whether that tool searches only on Github or on all repositories in the Internet? Hopefully it's the latter.