How to use the chiapos.Verifier function in chiapos

def verify_and_get_quality(self) -> Optional[bytes32]:
        v: Verifier = Verifier()
        plot_seed: bytes32 = self.get_plot_seed()
        quality_str = v.validate_proof(plot_seed, self.size, self.challenge_hash,
                                       bytes(self.proof))
        if not quality_str:
            return None
        return self.quality_str_to_quality(self.challenge_hash, quality_str)

async def request_header_hash(
        self, request: farmer_protocol.RequestHeaderHash
    ) -> OutboundMessageGenerator:
        """
        Creates a block body and header, with the proof of space, coinbase, and fee targets provided
        by the farmer, and sends the hash of the header data back to the farmer.
        """
        plot_seed: bytes32 = request.proof_of_space.get_plot_seed()

        # Checks that the proof of space is valid
        quality_string: bytes = Verifier().validate_proof(
            plot_seed,
            request.proof_of_space.size,
            request.challenge_hash,
            bytes(request.proof_of_space.proof),
        )
        assert quality_string

        async with self.store.lock:
            # Retrieves the correct head for the challenge
            heads: List[HeaderBlock] = self.blockchain.get_current_tips()
            target_head: Optional[HeaderBlock] = None
            for head in heads:
                assert head.challenge
                if head.challenge.get_hash() == request.challenge_hash:
                    target_head = head
            if target_head is None: