Method register_higher_order_function

datafusion/expr/src/registry.rs:246–253

(
        &mut self,
        function: Arc<HigherOrderUDF>,
    )

        Ok(self.udfs.insert(udf.name().to_string(), udf))
    }
    fn register_higher_order_function(
        &mut self,
        function: Arc<HigherOrderUDF>,
    ) -> Result<Option<Arc<HigherOrderUDF>>> {
        Ok(self
            .higher_order_functions
            .insert(function.name().into(), function))
    }
    fn register_udaf(
        &mut self,
        udaf: Arc<AggregateUDF>,