Function proof_size 

pub fn proof_size<F, VCS>(params: &FRIParams<F>, vcs: &VCS) -> usize
where
    F: BinaryField,
    VCS: MerkleTreeScheme<F>,

Exact byte-size of a FRI proof, including the initial commitment.

The size follows from the parameters alone, so the prover need not run.

Counted on the message channel:

• the initial codeword commitment;
• one commitment per fold round.

Counted on the decommitment channel:

• the terminal codeword, sent in the clear;
• the Merkle layer digests and the per-query branch digests;
• the field elements of every opened coset.