python-sfml简短示例中不明显的错误

Question

python-sfml入门。这段代码

import sfml

window = sfml.RenderWindow(sfml.VideoMode(640, 480), "FooBar")

try:
    texture = sfml.Texture.from_file("brick_002.jpg")
    sprite = sfml.Sprite(texture)

    font = sfml.Font.from_file("arial.ttf")
    text = sfml.Text("Math Rocks!")


except IOError:
    exit(1)

while window.is_open:
    for event in window.events:
        if type(event) is sfml.CloseEvent:
        window.close()

    window.clear()
    window.draw(sprite)
    window.draw(text)
    window.display()

并犯了这个错误：

Traceback (most recent call last):
  File "sfml.py", line 1, in <module>
    import sfml
  File "/home/montreal/projects/foo/sfml/sfml.py", line 4, in <module>
    window = sfml.RenderWindow(sfml.VideoMode(640, 480), "FooBar")
AttributeError: 'module' object has no attribute 'RenderWindow'

但是在翻译中，每个人的工作都很好（我可以创建窗口，添加纹理并关闭它）。什么可能是错的？