Bypassing network proxy in apt-get

Using apt-get command in proxy network results in an error ....
proxy authentication required.
This can be resolved by creating a configuration file in apt.
navigate to /etc/apt/apt.conf
open an editor by
nano apt.conf
add the following lines to the file
Acquire::protocol::proxy "protocol://username:password@proxy:port/";
where protocol is the network protocols like http,https,ftp,etc with wich you download the package.