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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 rangify(number_list):
 """Assumes the list is sorted."""

    if not number_list:
        return number_list

    ranges = []

    range_start = prev_num = number_list[0]
    for num in number_list[1:]:
        if num != (prev_num + 1):
            ranges.append((range_start, prev_num))
            range_start = num
        prev_num = num

    ranges.append((range_start, prev_num))
    return ranges