PROBLEM $2$: Progressive alignment $(1$ POINT$)$

Write a function that computes a multiple alignment of a set of sequences using the progressive alignment strategy. Your function should take in an "alignment order" which specifies the ordering of the pairwise alignments to perform. For example, if there are four sequences, the alignment order

$[((1,),(3,)),((0,),(2,)),((1,3),(0,2))]$

would specify the following sequence of pairwise alignments:

align sequence $1$ to sequence $3$

align sequence $0$ to sequence $2$

align the partial alignment of sequences $1$ and $3$ to the partial alignment of sequences $0$ and $2$