Close the _Stream object. No operation should be
           done on it afterwards.

def close(self):
        """Close the _Stream object. No operation should be
           done on it afterwards.
        """
        if self.closed:
            return

        if self.mode == "w" and self.comptype != "tar":
            self.buf += self.cmp.flush()

        if self.mode == "w" and self.buf:
            self.fileobj.write(self.buf)
            self.buf = b""
            if self.comptype == "gz":
                # The native zlib crc is an unsigned 32-bit integer, but
                # the Python wrapper implicitly casts that to a signed C
                # long.  So, on a 32-bit box self.crc may "look negative",
                # while the same crc on a 64-bit box may "look positive".
                # To avoid irksome warnings from the `struct` module, force
                # it to look positive on all boxes.
                self.fileobj.write(struct.pack("<L", self.crc & 0xffffffff))
                self.fileobj.write(struct.pack("<L", self.pos & 0xffffFFFF))

        if not self._extfileobj:
            self.fileobj.close()

        self.closed = True