The groups$\_$of$\_3()$ function takes a list of values and an integer value denoting a threshold. This

function will group the elements of the input list into groups depending on the threshold.

Example: If the threshold is three then, the list will be chopped into sub$-$lists each of length $3$ i$.$e$.,$ each

sublist will contain $3$ elements. $($i$.$e$.,$ the first three consecutive values form a group; the second three

form a group, etc.$).$ This function must return a list of lists where each sub$-$list $($excluding$,$ perhaps, the

last$)$ is a group containing number of elements equal to the threshold. If there are not enough values to

fill the last grouping, then it will contain fewer than the threshold value.

As examples, consider the following.

$$ groups$\_$of$\_3([1,2,3,4,5,6,7,8,9])$

$\left[\begin{array}{ccc}1& 2& 3\\ 4& 5& 6\\ 7& 8& 9\end{array}\right][[1,2,3],[4,5,6],[7,8]]$

Write TWO UNIT TEST for your function.