KeyInput :: keypad - Key on the keypad
The property is true, when a key on the keypad has been entered, and false otherwise.
Return value:  State of function return ( bool  )
A State true indicates, that the function was executed successfully. Otherwise state is false.
Implementation overview
- Get keypad key state
 KeyInput :: keypad (  )
- Change key on keypad state
 KeyInput :: keypad ( bState )

