Function to_substrait_rel
pub fn to_substrait_rel(
producer: &mut impl SubstraitProducer,
plan: &LogicalPlan,
) -> Result<Box<Rel>, DataFusionError>
pub fn to_substrait_rel(
producer: &mut impl SubstraitProducer,
plan: &LogicalPlan,
) -> Result<Box<Rel>, DataFusionError>