docs: function size(file, unit, digit) {
        if (fs.existsSync(file)) {
          if (isNum(unit)) digit = unit, unit = UDF;
          if (!isNum(digit)) digit = 2;
          var flSize = fs.statSync(file)['size'];
          var rlSize = match(unit, {
            'b': flSize,
            'kb': flSize / 1024,
            'mb': flSize / 1024 / 1024,
            'gb': flSize / 1024 / 1024 / 1024,
            'tb': flSize / 1024 / 1024 / 1024 / 1024,
            'default': flSize / 1024
          });
          return Number(rlSize).toFixed(digit);
        }
      }