def reverse_file(filename):
""" Overwrites given file with its content line-by-line reversed """
s = ArrayStack()
original = open(filename)
for line in original:
s.push(line.rstrip('\n'))
original.close()
new_filename = 'new_{}.txt'.format(randrange(0, 100, 2))
output = open(new_filename, 'w')
while not s.isEmpty():
output.write(s.pop() + '\n')
output.close()
