input: Write a function to generate a staircase pattern of height 'n', where 'n' is an integer input. The staircase should be right-aligned, composed of '#' characters, and have spaces on the left until it reaches the correct alignment.
  
  assert staircase(5) == '\n    #\n   ##\n  ###\n ####\n#####'
  assert staircase(3) == '\n  #\n ##\n###'
  assert staircase(1) == '\n#'
  assert staircase(0) == ''
  assert staircase(-1) == ''
output: def staircase(n):
      if n <= 0:
          return ''
      result = ''
      for i in range(1, n + 1):
          result += ' ' * (n - i) + '#' * i + '\n'
      return result[:-1]