code: def percentage(a, b, precision=1, mode=0):
      
      _a, _b = a, b
      pct = "{0:.{1}f}%".format(a * 100. / b, precision)
      a, b = thousands(a), thousands(b)
      if mode == 0:
          return "{0} of {1} ({2})".format(a, b, pct)
      elif mode == 1:
          return "{0} ({1})".format(a, pct)
      elif mode == 2:
          return _a * 100. / _b
      return pct
docs: >>> percentage(100, 200)
      '100 of 200 (50.0%)'