I am currently trying to install the kobuki package using:-

sudo apt-get install ros-kinetic-kobuki ros-kinetic-kobuki-core ros-kinetic-kobuki-gazebo

which is as mentioned in the tutorials in the following websites, http://wiki.ros.org/kobuki/Tutorials/Installation and http://wiki.ros.org/rrt_exploration/Tutorials . However in each case I get the error

E: Unable to locate package ros-kinetic-kobuki

E: Unable to locate package ros-kinetic-kobuki-core

E: Unable to locate package ros-kinetic-kobuki-gazebo

This is also true when I try to do the same using ROS melodic. Has this package been stopped or removed? or am I required to install something before installing these packages?