input: Write a function to generate the first n elements of the Sierpinski triangle. The function should print the triangle as a series of 1s and 0s.
  assert sierpinski_triangle(6)==None
  assert sierpinski_triangle(0)==None
  assert sierpinski_triangle(3)==None
  assert sierpinski_triangle(1)==None
output: def sierpinski_triangle(n):
      if n == 0:
          return
      triangle = ["0"]
      for i in range(1, n):
          new_row = ["0"]
          for j in range(1, len(triangle[i-1])):
              new_row.append(str(int(triangle[i-1][j-1]) ^ int(triangle[i-1][j])))
          new_row.append("0")
          triangle.append("".join(new_row))
      for row in triangle:
          print(row)