[Zope] ImplicitAcquirerWrapper Error

[beno]

Hi;
I'm trying to write a script and have this code:

folder = context.objectValues('Folder')
return len(folder)

When there are no folders in said folder, the answer comes back *0* (as one 
would expect). However, when I put a folder in there, I get this:

TypeError: cannot add type "ImplicitAcquirerWrapper" to string

What have I done wrong?
Also, I would actually like to count the number of DTMLMethods. To what do 
I change the first line of code?
Thank you for your patience and help,
beno