Write a Python script that translates an mRNA sequence into a protein. In other words,
your script should convert all codons into amino acids. 

The input is one sequence in FASTA format in a file called "dna.txt".

For example if the file contains 

>human
AUGAGGUACGCCGCCAGA

then the output should be MRYAAR.

Submit a hardcopy in class on Sept 23rd.