Python translating nucleotide to amino acid

Question

I have a function which doesn't work. I have to translate nucleotides sequence from .txt file into amino acids comparing string to dictionary. Can someone tell me what is wrong with this? The output shows only string from .txt file and it's supoosed to be amino acids sequence from this file.

f = open('hemoglobin.txt', 'r')
sequence = f.readline()
while sequence:
    sequence = sequence.rstrip()
    print(sequence)
    sequence = f.readline()

gencode = { 'ATA':'I', 'ATC':'I', 'ATT':'I', 'ATG':'M',
    'ACA':'T', 'ACC':'T', 'ACG':'T', 'ACT':'T',
    'AAC':'N', 'AAT':'N', 'AAA':'K', 'AAG':'K',
    'AGC':'S', 'AGT':'S', 'AGA':'R', 'AGG':'R',
    'CTA':'L', 'CTC':'L', 'CTG':'L', 'CTT':'L',
    'CCA':'P', 'CCC':'P', 'CCG':'P', 'CCT':'P',
    'CAC':'H', 'CAT':'H', 'CAA':'Q', 'CAG':'Q',
    'CGA':'R', 'CGC':'R', 'CGG':'R', 'CGT':'R',
    'GTA':'V', 'GTC':'V', 'GTG':'V', 'GTT':'V',
    'GCA':'A', 'GCC':'A', 'GCG':'A', 'GCT':'A',
    'GAC':'D', 'GAT':'D', 'GAA':'E', 'GAG':'E',
    'GGA':'G', 'GGC':'G', 'GGG':'G', 'GGT':'G',
    'TCA':'S', 'TCC':'S', 'TCG':'S', 'TCT':'S',
    'TTC':'F', 'TTT':'F', 'TTA':'L', 'TTG':'L',
    'TAC':'Y', 'TAT':'Y', 'TAA':'*', 'TAG':'*',
    'TGC':'C', 'TGT':'C', 'TGA':'*', 'TGG':'W' }

def translate(sequence):
    for i in range(0, len(sequence), 3):
        codon = str(sequence[i])
        if codon == gencode['TAA', 'TAG', 'TGA']:
            print('STOP')
            break
        elif codon == gencode[key]:
            print(gencode[value])
    return()

Answer 1

You're not calling the translate() function.

while sequence:
    sequence = sequence.rstrip()
    translate(sequence)

Answer 2

change this:

if codon == gencode['TAA', 'TAG', 'TGA']:

to:

if codon in ['TAA', 'TAG', 'TGA']: