Insert the following key values, in the order given, into an initially empty B$-$Tree of order $2$:

$21,15,18,40,51,64,79,45,22,37,4,55,12,$

$5,91,19,28,81,72$

i$.$ Draw the tree after inserting $72$ and show your workings.

ii$.$ B$-$Tree is typically used to index a column with unique val$-$ ues. How would you use B$-$Tree to index a column that has duplicated values, e$.$g$.$ this list of keys: $2,10,5,5,6,9.$