docs: function normalizeCharacterBrightness(darkPixelsByCharacter) {
    let min = Infinity;
    let max = 0;
    for (const char in darkPixelsByCharacter) {
      const b = darkPixelsByCharacter[char];
      min = b < min ? b : min;
      max = b > max ? b : max;
    }
  
    if (max === 0) {
      throw Error('Characters are blank');
    }
  
    const brightness = {};
    for (const char in darkPixelsByCharacter) {
      const b = darkPixelsByCharacter[char];
      brightness[char] = Math.floor((max - b) / (max - min) * 255);
    }
    return brightness;
  }