Basically the request object that each function gets as its first
argument (called 'web' in examples) has a method called input(). If
you do web.input(), you get back a dict of all form fields and query
string arguments. If you have a form field named 'x' you can do
web.input('x') to get just its value. If you have multiple form
fields named 'x' you'll get back a list of values.