reversing data using stack as consequence of the lifo protocola stack can be used as general tool to reverse data sequence for exampleif the values and are pushed onto stack in that orderthey will be popped from the stack in the order and then this idea can be applied in variety of settings for examplewe might wish to print lines of file in reverse order in order to display data set in decreasing order rather than increasing order this can be accomplished by reading each line and pushing it onto stackand then writing the lines in the order they are popped an implementation of such process is given in code fragment def reverse file(filename) """overwrite given file with its contents line-by-line reversed "" arraystack original open(filename for line in originalwe will re-insert newlines when writing push(line rstrip\ ) original close now we overwrite with contents in lifo order reopening file overwrites original output open(filenamew while not is empty) output write( pop\ re-insert newline characters output closecode fragment function that reverses the order of lines in file one technical detail worth noting is that we intentionally strip trailing newlines from lines as they are readand then re-insert newlines after each line when writing the resulting file our reason for doing this is to handle special case in which the original file does not have trailing newline for the final line if we exactly echoed the lines read from the file in reverse orderthen the original last line would be followed (without newlineby the original second-to-last line in our implementationwe ensure that there will be separating newline in the result the idea of using stack to reverse data set can be applied to other types of sequences for exampleexercise - explores the use of stack to provide yet another solution for reversing the contents of python list ( recursive solution for this goal was discussed in section more challenging task is to reverse the order in which elements are stored within stack if we were to move them from one stack to anotherthey would be reversedbut if we were to then replace them into the original stackthey would be reversed againthereby reverting to their original order exercise - explores solution for this task