new_contents: import string
  
  def checkio(numStr, radix):
      if type(numStr) not in (str, unicode):
          raise TypeError("number must be in a string format")
      if type(radix) is not int:
          raise TypeError("radix expected to be an int")
      
      # generate radix dictionary
      radixDict = { }
      alphaIndex = 0
      for i in range(radix):
          if i > 9:
              radixDict[string.ascii_lowercase[alphaIndex]] = i
              alphaIndex += 1
          else:
              radixDict[str(i)] = i
      
      # get the result
      result = 0
      numStrLen = len(numStr)
      for i in reversed(range(numStrLen)):
          digit = numStr[i].lower()
          if digit not in radixDict:
              return -1
          result += radixDict[digit] * pow(radix, numStrLen - 1 - i)
      return result
  
subject: Create mySolution.py