pub fn preprocessed_chip_ids(&self) -> Vec<usize> {
        self.chips
            .iter()
            .enumerate()
            .filter(|(_, chip)| chip.preprocessed_width() > 0)
            .map(|(i, _)| i)
            .collect()
    }
Returns the id of all chips in the machine that have preprocessed columns.
crates/stark/src/machine.rs