[Zope] binding to 'context' from a Python product

I've reading Zope documentation and python/lib modules and have not found a way to bind to the current folder context when I run my python product in Zope 2.7. I'm creating the product with a member function, ex(). So for example, if my product is 'sample' and the member function is 'ex', I try executing 'sample.ex()'. Inside ex(), I have the following code: def ex(self): request = context.REQUEST The product loads ok, but when ex() is called, I get an error message: Error Type: NameError Error Value: global name 'context' is not defined Thanks in advance for any tips.