docs: function sign(secretKey, text) {
      const sec = parseSecretKey(secretKey);
      const bintext = Buffer.from(text, 'utf8');
      const sig = nacl.sign.detached(bintext, sec.key);
      // Full signature includes algorithm id ('Ed'), key number,
      // and the signature itself.
      const fullsig = new Uint8Array(2 + 8 + 64);
      fullsig[0] = 69 // 'E'
      fullsig[1] = 100; // 'd'
      fullsig.set(sec.num, 2) // key number
      fullsig.set(sig, 10); // signature
      return Buffer.from(fullsig.buffer).toString('base64');
  }