def get_open_file(self, file_des):
        """Return an open file.

        Args:
            file_des: File descriptor of the open file.

        Raises:
            OSError: an invalid file descriptor.
            TypeError: filedes is not an integer.

        Returns:
            Open file object.
        """
        if not is_int_type(file_des):
            raise TypeError('an integer is required')
        if (file_des >= len(self.open_files) or
                self.open_files[file_des] is None):
            self.raise_os_error(errno.EBADF, str(file_des))
        return self.open_files[file_des][0]
Return an open file.

        Args:
            file_des: File descriptor of the open file.

        Raises:
            OSError: an invalid file descriptor.
            TypeError: filedes is not an integer.

        Returns:
            Open file object.