A simple example

Let's start with a simple circuit, to introduce you to the common APIs and how they are used. The circuit will take a public input $c$, and will prove knowledge of two private inputs $a$ and $b$ such that

$$a\cdot b=c.$$

#![allow(unused)]
fn main() {
extern crate halo2;
use halo2::arithmetic::FieldExt;

struct MyCircuit<F: FieldExt> {
    a: F,
    b: F,
}
}

TODO