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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 titleCounts(readsAlignments):
 """ Count the number of times each title in a readsAlignments instance is matched. This is useful for rapidly discovering what titles were matched and with what frequency. @param readsAlignments: A L{dark.alignments.ReadsAlignments} instance. @return: A C{dict} whose keys are titles and whose values are the integer counts of the number of reads that matched that title. """


    titles = defaultdict(int)
    for readAlignments in readsAlignments:
        for alignment in readAlignments:
            titles[alignment.subjectTitle] += 1
    return titles