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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 summarizePosition(self, index):
 """ Compute residue counts at a specific sequence index. @param index: an C{int} index into the sequence. @return: A C{dict} with the count of too-short (excluded) sequences, and a Counter instance giving the residue counts. """

        countAtPosition = Counter()
        excludedCount = 0

        for read in self:
            try:
                countAtPosition[read.sequence[index]] += 1
            except IndexError:
                excludedCount += 1

        return {
            'excludedCount': excludedCount,
            'countAtPosition': countAtPosition
        }