pub fn exp_f_bits(&mut self, x: Felt<C::F>, power_bits: Vec<Var<C::N>>) -> Felt<C::F> {
        let mut result = self.eval(C::F::one());
        let mut power_f: Felt<_> = self.eval(x);
        for i in 0..power_bits.len() {
            let bit = power_bits[i];
            let tmp = self.eval(result * power_f);
            result = self.select_f(bit, tmp, result);
            power_f = self.eval(power_f * power_f);
        }
        result
    }
Exponentiates a felt to a list of bits in little endian.
crates/recursion/compiler/src/ir/utils.rs