I want to install libgflags-dev. According to this launchpad link, it is present in the ubuntu repositories : <https://launchpad.net/ubuntu/+source/gflags> and <http://packages.ubuntu.com/raring/libdevel/libgflags-dev> 

But when i try to sudo apt-get install it, I get `E: Unable to locate package libgflags-dev` 
Why is this happening ? I have all multiverse and universe enabled from software center. 

How to install it from apt-get ? 

P.S. I know i can simply download the binary and make install it, but I want to know how to do this from apt-get.