Problems using quickly text entry box

Question

I'm trying to follow the 'creating your first ubuntu app' tutorial. I'm making a text entry box and every time I hit enter it doesn't work. Here is my code:

def on_urlentry_activate(self, widget):
    url = widget.get_text()

    print url()
    self.webview.open(url)

and this is what I get:

File "/home/leife/mybrowser1/mybrowser1/Mybrowser1Window.py", line 50, in on_urlentry_activate
print url()
TypeError: 'str' object is not callable

I tried seeing if compiling the glade source code would help, but someone else said it wouldn't.