text: const range = (from, to) => {
    let res = [];
    from = from.charCodeAt(0);
    to = to.charCodeAt(0);
    for (let i = from; i <= to; i++) {
      res.push(String.fromCharCode(i));
    }
    return res;
  };
  
  const randInt = (max) => {
    return Math.floor(Math.random() * max);
  };
  
  const chars = [...range('0', '9'), 
                 ...range('a', 'z'),
                 ...range('A', 'Z')];
  
  const nbChars = chars.length;
  
  const nextChar = () => chars[randInt(nbChars)];
  const nextString = len => {
    let res = "";
    for (let i = 0; i < len; i++) {
      res += nextChar();
    }
    return res;
  };
  
  module.exports = {
    nextChar,
    nextString
  };
  