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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 bz2open(cls, name, mode="r", fileobj=None, compresslevel=9, **kwargs):
 """Open bzip2 compressed tar archive name for reading or writing. Appending is not allowed. """

        if len(mode) > 1 or mode not in "rw":
            raise ValueError("mode must be 'r' or 'w'.")

        try:
            import bz2
        except ImportError:
            raise CompressionError("bz2 module is not available")

        if fileobj is not None:
            fileobj = _BZ2Proxy(fileobj, mode)
        else:
            fileobj = bz2.BZ2File(name, mode, compresslevel=compresslevel)

        try:
            t = cls.taropen(name, mode, fileobj, **kwargs)
        except (IOError, EOFError):
            fileobj.close()
            raise ReadError("not a bzip2 file")
        t._extfileobj = False
        return t