def gccontent(sequence):
    """Return the percent GC content of an 
       unambiguous nucleotide SEQUENCE"""
    total = len(sequence)
    gccount = 0

    for base in sequence:
        if 'G' == base or 'C' == base:
            gccount = gccount + 1
    
    return 100.0 * gccount / total

seq1 = "ATCGGACCTACGCCTCAAGCACCTACATCCCGATAGAAGACCCTTTT"
seq2 = "ATCGGACCCCGTAGACAATTCAAGCACCTACATCCCGATAGAAGACCCTTTT"
seq3 = "GACCATACTGCCTCCAAGCAGCCTAACAATCCCCGTATGAGGAAGAACCC"

print seq1, gccontent(seq1)
print seq2, gccontent(seq2)
print seq3, gccontent(seq3)