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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 natural_sort(item):
 """ Sort strings that contain numbers correctly. Works in Python 2 and 3. "['v1.2.1', 'v1.2.3', 'v1.2.5', 'v1.2.15', 'v1.3.3', 'v1.3.12']" """

    dre = re.compile(r'(\d+)')
    return [int(s) if s.isdigit() else s.lower() for s in re.split(dre, item)]