input: Write a function to print a staircase of height 'n', where n is an integer. The staircase should be aligned to the right with '#' symbols and spaces filling the left side. Each step of the staircase should be one '#' symbol wider than the previous step. If the input n is 0, the function should not print anything.
  assert staircase(5)
  assert staircase(3)
  assert staircase(0)
  assert staircase(1)
  assert staircase(2)
output: def staircase(n):
      for i in range(1, n + 1):
          print(' ' * (n - i) + '#' * i)