def swap$\_$ends$($message: str$)=>str$ :

$"$w$"$ "Return a new string that is message with the first and last

characters swapped.

Precondition: len$($message$)2$

$$ swap$\_$ends $(\text{'}$cat$\text{'})$

'tac"

$)$ swap$\_$ends $(\text{'}$breakfast for dinnerl'$)$

'Ireakfast for dinnerb'

nen

return swap$\_$ends $($message: last$\_$char $+$ middle $+$ first$\_$char$)$

return last$\_$char $+$ middle $+$ first$\_$char