render

The field as a line of a shredding schema, in the specification's own shape.

Deliberately not a Parquet schema file: this project writes no Parquet and takes no dependency on one, so emitting something that looked like a complete schema would be a claim about a format it does not own. What this is, is the one line a reader needs to transcribe, with the decision that is easy to get wrong — whether variant_value can be dropped — already made.