Write a function called matrix$\_$classifier that has one input called Matrix$1$ represented as a numpy array. The function should classify the matrix as one of $($i$)$ one$-$to$-$one, $($ii$)$ onto, $($iii$)$ both $($i$.$e$.$ invertible$),$ or $($iv$)$ neither. It should return the classification represented as a string $($i$.$e$.$ either "one$-$to$-$one", "onto", "invertible", or "neither"$).$