How to use the sodium-native.crypto_hash_sha256 function in sodium-native

function Mac (secret) {
  var hash = Buffer.alloc(sodium.crypto_hash_sha256_BYTES)
  sodium.crypto_hash_sha256(hash, Buffer.from(secret))

  return hash
    .toString('hex')
    .slice(-1 * MAC_LENGTH)
}

function Mac (secret) {
  var hash = Buffer.alloc(sodium.crypto_hash_sha256_BYTES)
  sodium.crypto_hash_sha256(hash, Buffer.from(secret))

  return hash
    .toString('hex')
    .slice(-1 * MAC_LENGTH)
}

exports.sha256 = function hashSha256 (input) {
  if (!(input instanceof Buffer)) {
    throw new Error('input must be a Buffer')
  }
  const output = Buffer.alloc(sodium.crypto_hash_sha256_BYTES)
  sodium.crypto_hash_sha256(output, input)
  return output
}