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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 _init_read_gz(self):
 """Initialize for reading a gzip compressed fileobj. """

        self.cmp = self.zlib.decompressobj(-self.zlib.MAX_WBITS)
        self.dbuf = b""

        # taken from gzip.GzipFile with some alterations
        if self.__read(2) != b"\037\213":
            raise ReadError("not a gzip file")
        if self.__read(1) != b"\010":
            raise CompressionError("unsupported compression method")

        flag = ord(self.__read(1))
        self.__read(6)

        if flag & 4:
            xlen = ord(self.__read(1)) + 256 * ord(self.__read(1))
            self.read(xlen)
        if flag & 8:
            while True:
                s = self.__read(1)
                if not s or s == NUL:
                    break
        if flag & 16:
            while True:
                s = self.__read(1)
                if not s or s == NUL:
                    break
        if flag & 2:
            self.__read(2)