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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 create(cls, ltfile):
 """Create a livetime cube from a single file or list of files."""


        if not re.search('\.txt?', ltfile) is None:
            files = np.loadtxt(ltfile, unpack=True, dtype='str')
        elif not isinstance(ltfile, list):
            files = glob.glob(ltfile)

        ltc = cls.create_from_fits(files[0])
        for f in files[1:]:
            ltc.load_ltfile(f)

        return ltc