EXERCISE $9$: complete the following definition of a function that splits

$//$ a list into a pair of two lists. The offset for the the split position

$//$ is given by the Int argument.

$//$

$//$ The behavior is determined by:

$//$

$//$ for all n$,$ xs:

$//$ splitAt $($n$,$ xs$)==($xs$.$take$($n$),$ xs$.$drop$($n$))$