I wrote that.

 def checkio(data):
        i = 0
        result = 0
        if data[i] < len(data):
            result += data[i]
            chekio(data[i+1])
    else:
        return result

But more i can't move, becouse error message write me: NameError: name 'chekio' is not defined, checkio, 6 But i see example recoursive function, they not contained that. Please, choose right path to solution that mission.