Write a Python script that reads in two unaligned sequences in FASTA
format from a file called "dna_fasta.txt" and outputs the optimal
alignment scoring matrix V and the corresponding traceback T. Recall that
the matrix V contains the score of the optimal alignment of the two input
sequences and all substrings from the start. Submit a hardcopy on Feb
24rth in class.

Recall the code for computing V and T is

Input: seq1 (along columns), seq2 (along rows)

Initilization: 
V[0,0]=0, V[i,0]=ig, V[0,j]=jg
T[0,0]=0, T[i,0]='L', V[0,j]='U'

Recurrence:

for i = 0 to length of seq2:
	for j = 0 to length of seq1:
		x = V[i-1,j-1]+m/mm
		y = V[i-1,j]+g
		z = V[i,j-1]+g
                if x >= y and x >= z:
			V[i][j]=x
			T[i][j]='D'
		elif y >= x and y >= z:
			V[i][j]=y
			T[i][j]='U'
		else:
			V[i][j]=z
			T[i][j]='L'