thank you, this looks like a good start into building extensions...
Please also follow the naming conventions, which is UpperCamelCase for property, method and event names (i.e. the first letter should be a capital letter) and lowerCamelCase for parameter names, no underscores .
example
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.