How to use the @ethersproject/sha2.sha256 function in @ethersproject/sha2

// This byte will complete an 11-bit index
        } else {
            indices[indices.length - 1] <<= remainingBits;
            indices[indices.length - 1] |= entropy[i] >> (8 - remainingBits);

            // Start the next word
            indices.push(entropy[i] & getLowerMask(8 - remainingBits));

            remainingBits += 3;
        }
    }

    // Compute the checksum bits
    const checksumBits = entropy.length / 4;
    const checksum = arrayify(sha256(entropy))[0] & getUpperMask(checksumBits);

    // Shift the checksum into the word indices
    indices[indices.length - 1] <<= checksumBits;
    indices[indices.length - 1] |= (checksum >> (8 - checksumBits));

    if (!wordlist) { wordlist = wordlists["en"]; }

    return wordlist.join(indices.map((index) => wordlist.getWord(index)));
}

indices[indices.length - 1] <<= 8;
            indices[indices.length - 1] |= entropy[i];
            remainingBits -= 8;
            // This byte will complete an 11-bit index
        }
        else {
            indices[indices.length - 1] <<= remainingBits;
            indices[indices.length - 1] |= entropy[i] >> (8 - remainingBits);
            // Start the next word
            indices.push(entropy[i] & getLowerMask(8 - remainingBits));
            remainingBits += 3;
        }
    }
    // Compute the checksum bits
    const checksumBits = entropy.length / 4;
    const checksum = arrayify(sha256(entropy))[0] & getUpperMask(checksumBits);
    // Shift the checksum into the word indices
    indices[indices.length - 1] <<= checksumBits;
    indices[indices.length - 1] |= (checksum >> (8 - checksumBits));
    if (!wordlist) {
        wordlist = wordlists["en"];
    }
    return wordlist.join(indices.map((index) => wordlist.getWord(index)));
}
export function isValidMnemonic(mnemonic, wordlist) {

function base58check(data: Uint8Array): string {
    return Base58.encode(concat([ data, hexDataSlice(sha256(sha256(data)), 0, 4) ]));
}

for (var i = 0; i < words.length; i++) {
        var index = wordlist.getWordIndex(words[i].normalize("NFKD"));
        if (index === -1) {
            throw new Error("invalid mnemonic");
        }
        for (var bit = 0; bit < 11; bit++) {
            if (index & (1 << (10 - bit))) {
                entropy[offset >> 3] |= (1 << (7 - (offset % 8)));
            }
            offset++;
        }
    }
    var entropyBits = 32 * words.length / 3;
    var checksumBits = words.length / 3;
    var checksumMask = getUpperMask(checksumBits);
    var checksum = bytes_1.arrayify(sha2_1.sha256(entropy.slice(0, entropyBits / 8)))[0] & checksumMask;
    if (checksum !== (entropy[entropy.length - 1] & checksumMask)) {
        throw new Error("invalid checksum");
    }
    return bytes_1.hexlify(entropy.slice(0, entropyBits / 8));
}
exports.mnemonicToEntropy = mnemonicToEntropy;

function base58check(data) {
    return Base58.encode(concat([data, hexDataSlice(sha256(sha256(data)), 0, 4)]));
}
const _constructorGuard = {};

function base58check(data) {
    return basex_1.Base58.encode(bytes_1.concat([data, bytes_1.hexDataSlice(sha2_1.sha256(sha2_1.sha256(data)), 0, 4)]));
}
var _constructorGuard = {};

if (index === -1) { throw new Error("invalid mnemonic"); }

        for (let bit = 0; bit < 11; bit++) {
            if (index & (1 << (10 - bit))) {
                entropy[offset >> 3] |= (1 << (7 - (offset % 8)));
            }
            offset++;
        }
    }

    const entropyBits = 32 * words.length / 3;

    const checksumBits = words.length / 3;
    const checksumMask = getUpperMask(checksumBits);

    const checksum = arrayify(sha256(entropy.slice(0, entropyBits / 8)))[0] & checksumMask;

    if (checksum !== (entropy[entropy.length - 1] & checksumMask)) {
        throw new Error("invalid checksum");
    }

    return hexlify(entropy.slice(0, entropyBits / 8));
}