'Submits the form.  If ``name`` is given, then also select that
button (using ``index`` to disambiguate)``.
Any extra keyword arguments are passed to the ``.get()`` or
``.post()`` method.
Returns a response object.'

def submit(self, name=None, index=None, **args):

    fields = self.submit_fields(name, index=index)
    return self.response.goto(self.action, method=self.method, params=fields, **args)
