def is_nullable(field: SchemaDict) -> bool:
    """Check if a Pydantic FieldInfo is nullable."""
    return (
        "anyOf" in field
        and len(field["anyOf"]) == 2
        and {"type": "null"} in field["anyOf"]
    )
Check if a Pydantic FieldInfo is nullable.
src/_bentoml_impl/arrow.py