How to use the vdirsyncer.exceptions.AlreadyExistingError function in vdirsyncer

def _upload_impl(self, item, href):
        fpath = self._get_filepath(href)
        try:
            with atomic_write(fpath, mode='wb', overwrite=False) as f:
                f.write(item.raw.encode(self.encoding))
                return fpath, get_etag_from_file(f)
        except OSError as e:
            if e.errno == errno.EEXIST:
                raise exceptions.AlreadyExistingError(existing_href=href)
            else:
                raise

def upload(self, item):
        href = self._get_href(item)
        if href in self.items:
            raise exceptions.AlreadyExistingError(existing_href=href)
        etag = _random_string()
        self.items[href] = (etag, item)
        return href, etag

def upload(self, item):
        href = item.ident
        if href in self._items:
            raise exceptions.AlreadyExistingError(existing_href=href)

        self._items[href] = item, item.hash
        return href, item.hash

def check_error(e):
    try:
        errors.check_exception(e[0])
    except errors.Error.ItemNotFound as e:
        raise exceptions.NotFoundError(e) from e
    except errors.Error.ItemAlreadyExisting as e:
        raise exceptions.AlreadyExistingError(e) from e
    except errors.Error.WrongEtag as e:
        raise exceptions.WrongEtagError(e) from e
    except errors.Error.ReadOnly as e:
        raise exceptions.ReadOnlyError(e) from e
    except errors.Error.UnsupportedVobject as e:
        raise exceptions.UnsupportedVobjectError(e) from e
    except (errors.Error.BadDiscoveryConfig,
            errors.Error.BadCollectionConfig) as e:
        raise TypeError(e) from e
    except errors.Error.MetadataValueUnsupported as e:
        raise exceptions.UnsupportedMetadataError(e) from e

def upload(self, item):
        try:
            entry = self._item_type.create(self._journal.collection, item.raw)
            entry.save()
        except etesync.exceptions.DoesNotExist as e:
            raise exceptions.NotFoundError(e)
        except etesync.exceptions.AlreadyExists as e:
            raise exceptions.AlreadyExistingError(e)
        return item.uid, item.hash