def METHOD_NAME(self) -> None:
    if self.__callback:
        if self.__buf.tell() == 0:
            # Empty file:
            result = b""
        else:
            # Return the data without actually loading it into memory,
            # relying on Python's buffer API and mmap(). mmap() just gives
            # a view directly into the filesystem's memory cache, so it
            # doesn't result in duplicate memory use.
            self.__buf.seek(0, 0)
            result = memoryview(
                mmap.mmap(self.__buf.fileno(), 0, access=mmap.ACCESS_READ)
            )
        self.__callback(result)
    # We assign this to None here, because otherwise we can get into
    # really tricky problems where the CPython interpreter dead locks
    # because the callback is holding a reference to something which
    # has a __del__ method. Setting this to None breaks the cycle
    # and allows the garbage collector to do it's thing normally.
    self.__callback = None
    # Closing the temporary file releases memory and frees disk space.
    # Important when caching big files.
    self.__buf.close()