Write a Python program that prints column numbers that are at least 50%
conserved. A column that is at least 50% conserved is one which has at
least 50% number of A's, C's, G's, or T's. For example if the multiple
alignment below is given in dna.fasta 

>human
ATCC
>mouse
AAGG
>cat
TGCA
>dog
ACAT

then the output would be 

0 2

because column number 0 has 75% A's and column 2 has 50% C's.

You solution should work for any number of sequences and any 
sequence length. Submit your solution in class on Dec 7th 2010.