Method nullable

datafusion/physical-expr/src/expressions/lambda_variable.rs:88–90

(&self, _input_schema: &Schema)

    }

    fn nullable(&self, _input_schema: &Schema) -> Result<bool> {
        Ok(self.field.is_nullable())
    }

    fn evaluate(&self, batch: &RecordBatch) -> Result<ColumnarValue> {
        if self.index >= batch.num_columns() {