Allow trailing comma in learning rate

        self.rates = []

        self.it = 0

        self.maxit = 0

        try:

            for i, pair in enumerate(pairs):

                if not pair.strip():

                    continue

                tmp = pair.split(':')

                if len(tmp) == 2:

                    step = int(tmp[1])

                    self.rates.append((float(tmp[0]), max_steps))

                    self.maxit += 1

                    return

            assert self.rates

        except (ValueError, AssertionError):

            raise Exception("Invalid learning rate schedule")

    def __iter__(self):

        return self