class directionEntry():
    def __init__(self,step_number,previous_Step,next_step):
        self.step_number = step_number
        self.previous_step = previous_Step
        self.next_step = next_step
    def getNext(self):
        return self.next_step

directionStepEntry10100297332 = directionEntry(1,None,2)
directionStepEntry10100297342 = directionEntry(2,1,3)
directionStepEntry10100297372 = directionEntry(3,2,4)
directionStepEntry10100297432 = directionEntry(4,3,None)

series_of_steps =[directionStepEntry10100297332,directionStepEntry10100297342,directionStepEntry10100297372,directionStepEntry10100297432]

next_step = series_of_steps[0].next_step
direction_entry_index = 0
while direction_entry_index < len(series_of_steps)-1:
    if next_step != None:
        print("The next step is step number:",series_of_steps[direction_entry_index].next_step)
    next_step = series_of_steps[direction_entry_index].next_step
    direction_entry_index += 1