######################################################################
##### READ IN FASTA FILE AND STORE CONTENTS IN *SEQUENCE* ############
######################################################################

file = open("hemoglobin.txt")

# Read in first line of file and check for FASTA format
headerLine = file.readline()
if (headerLine[0] == '>'):  # First character is '>'
    print "The file is in FASTA format."
else:
    print "The file is not in FASTA format."

# Read in the rest of the file (i.e., the sequence)
sequence = file.read()

# Remove all carriage returns from the sequence
sequence = sequence.replace("\n", "")



######################################################################
##### PRINT OUT *SEQUENCE* THREE NUCLEOTIDES AT A TIME ###############
######################################################################

# Assuming we have a coding sequence, print out each codon
startOfCodon = 0
while (startOfCodon < len(sequence)):
    codon = sequence[startOfCodon:startOfCodon+3]
    print codon
    startOfCodon = startOfCodon + 3