\subsubsection parameters ROS parameters

Reads and maintains the following parameters on the ROS server

- \b "~message" : \b [str] The message. min: , default: hello, max: 
- \b "~a" : \b [int] First number. min: -100, default: 1, max: 100
- \b "~b" : \b [int] First number. min: -100, default: 2, max: 100