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const charTable = '0123456789abcdefghijklmnopqrstuv';
export function encode(plain: Uint8Array): string {  let i = 0;  let shiftIndex = 0;  let digit = 0;  let encoded = '';  const {length} = plain;
  // byte by byte isn't as pretty as quintet by quintet but tests a bit  // faster. will have to revisit.  while (i < length) {    const current = plain[i];
    if (shiftIndex > 3) {      digit = current & (0xff >> shiftIndex);      shiftIndex = (shiftIndex + 5) % 8;      digit =        (digit << shiftIndex) |        ((i + 1 < length ? plain[i + 1] : 0) >> (8 - shiftIndex));      i++;    } else {      digit = (current >> (8 - (shiftIndex + 5))) & 0x1f;      shiftIndex = (shiftIndex + 5) % 8;      if (shiftIndex === 0) {        i++;      }    }
    encoded += charTable[digit];  }
  // No padding!  return encoded;}