Write a Python script that aligns two sequences X and Y such that the 
3rd nucleotide of X always aligns to the 5th one of Y and the 4th of
X always aligns to the 6th of Y. Start with Problem 4 of Exam 1. 

You will need to add two more conditions "elif" conditions to make this work.
You only need to modify the computeVandT function and leave traceback
as it is. The input to your program are two unaligned sequences in FASTA
format in a file called "dna_fasta.txt".

Submit a hardcopy on Mar 29th in class.