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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 read_ring_images_index():
 """Filter cumulative index for ring images. This is done by matching the column TARGET_DESC to contain the string 'ring' Returns ------- pandas.DataFrame data table containing only meta-data for ring images """

    meta = read_cumulative_iss_index()
    ringfilter = meta.TARGET_DESC.str.contains("ring", case=False)
    return meta[ringfilter]