input: Write a function to print a staircase of height 'n' using '#' and spaces. The staircase should be right-aligned and each step should consist of '#' characters. If the input height is 'n', the output should be a staircase with 'n' steps where each step uses one more '#' than the previous one.
  assert staircase(5)==None
  assert staircase(3)==None
  assert staircase(0)==None
  assert staircase(1)==None
  assert staircase(7)==None
output: def staircase(n):
      for i in range(1, n + 1):
          print(' ' * (n - i) + '#' * i)