input: Write a function to print a staircase of height 'n' where 'n' is an integer. The staircase should be right-aligned and consist of '#' characters. If 'n' is 0, the function should print nothing.
  assert staircase(5)
  assert staircase(3)
  assert staircase(0)
output: def staircase(n):
      for i in range(1, n + 1):
          print(' ' * (n - i) + '#' * i)