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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 _validate_completeness(self):
 """ Verify that the actual file manifests match the files in the data directory """

        errors = list()

        # First we'll make sure there's no mismatch between the filesystem
        # and the list of files in the manifest(s)
        only_in_manifests, only_on_fs, only_in_fetch = self.compare_manifests_with_fs_and_fetch()
        for path in only_in_manifests:
            e = FileMissing(path)
            LOGGER.warning(force_unicode(e))
            errors.append(e)
        for path in only_on_fs:
            e = UnexpectedFile(path)
            LOGGER.warning(force_unicode(e))
            errors.append(e)
        for path in only_in_fetch:
            e = UnexpectedRemoteFile(path)
            # this is non-fatal according to spec but the warning is still reasonable
            LOGGER.warning(force_unicode(e))

        if errors:
            raise BagValidationError(_("Bag validation failed"), errors)