input: Write a function to print a staircase of height 'n', where n is an integer. If the given integer is less than or equal to 0, print an empty string.
  def staircase(n):
      if n <= 0:
          print("")
      else:
          for i in range(0, n): 
              for j in range(0, n - i - 1): 
                  print(end=" ") 
              for j in range(0, i + 1): 
                  print("#", end="") 
              print("\r")
  
  assert staircase(5)
  assert staircase(0)==""
  assert staircase(-3)==""
output: def staircase(n):
      if n <= 0:
          print("")
      else:
          for i in range(0, n): 
              for j in range(0, n - i - 1): 
                  print(end=" ") 
              for j in range(0, i + 1): 
                  print("#", end="") 
              print("\r")