def main():
tab = Tab()
history = History()
tab.setUrl("http://tutorialspoint.com")
history.add(tab.saveUrl())
tab.setUrl("https://www.python.org/doc/")
history.add(tab.saveUrl())
tab.setUrl("http://www.trome.com.pe")
print("Current web url: " + tab.getUrl())
print("Back button is clicked.. ")
tab.restoreFromSavedUrl(history.get(1))
print("Saved url: " + tab.getUrl())
print("Back button again.. ")
tab.restoreFromSavedUrl(history.get(0))
print("Saved url: " + tab.getUrl())
