[Zope] append() and spaces

[Sven Hohage]

Hallo,
I've got a strange problem.
I use RESPONSE.redirect and pass values the usual way -->
('car?bought=1&amount=%s')%(Amount)
where Amount is a list-variable.
I build Amount dynamically with the append-method, and 
strangely I can't pass this variable(Error: Bad Request) because Python
puts 
spaces between the values ->[1, 3, 4]
So, I have to extract the list and build a new string but this is very
uncomfortable!
Any hint?
Thanks!