code: function unescapeString(str) {
      let i = 0, result = '';
      const len = str.length;
  
      while (i < len) {
          const ch = str[i++];
          result += (ch === '\\') ? (str[i++] || '') : ch;
      }
  
      return result;
  }
docs: Unescapes characters, screened with `\`, in given string
  @param  {String} str
  @return {String}