Minor Description
It looks there are private functions that look not used in the main codes -
_split_schema_abstract, _parse_field_abstract, _parse_schema_abstract and _infer_schema_type, located in python/pyspark/sql/types.py.
This looks not used from the first place -
https://github.com/apache/spark/commit/880eabec37c69ce4e9594d7babfac291b0f93f50.
Look we could remove this out.