Redo import logic for optional *_write_block functions (#436)
Redo import logic for optional *_write_block functions (#436)

* Redo optional blocker writer import logic

* Typo

Co-authored-by: Daniel Woodlins <1c6c8061e1ebe35b2047026c5569fd231b1ff4e5@braincorporation.com>
fastavro/fastavro,fastavro/fastavro