fn get_var<F>( evals: &ProofEvaluations<[F; 2]>, ) -> impl Fn(Column, CurrOrNext) -> F + '_where F: Field,
https://github.com/MinaProtocol/mina/blob/aebd4e552b8b4bcd78d1e24523169e8778794857/src/lib/pickles/plonk_checks/plonk_checks.ml#L97-L130