* change interface to discriminated union
* fix ts errors
* use definite assertion operator
* use | undefined, instead of assertion operator
* correct the button press arguments for dial button
* update props to have `Props` suffix
* add comment
* remove unnecessary default
* remove unnecessary comment
* make classname match filename
* setup test file
* export consts for testing
* add initial test
* add another DialPad test
* fix imports
