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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def findCodons(seq, codons):
 """ Find all instances of the codons in 'codons' in the given sequence. seq: A Bio.Seq.Seq instance. codons: A set of codon strings. Return: a generator yielding matching codon offsets. """

    seqLen = len(seq)
    start = 0
    while start < seqLen:
        triplet = str(seq[start:start + 3])
        if triplet in codons:
            yield start
        start = start + 3