def score_seq(motif, seq):
    """
    Given:
    motif: list of dictionaries of nucleotide --> probability
    seq: str of part of read sequence must be same length as motif
    Return:
    score: float of probability that it would be sampled from motif
    """
    score= 1
    for x in range(len(motif)):
        #no N's allowed in motif
        try:
            #bayes rule transition
            score = score*motif[x][seq[x]]
        except KeyError:
            return 0
    return score