'Return a list of tuples of the field values for the form.
This is suitable to be passed to ``urllib.urlencode()``.'

def form_values(self):

    results = []
    for el in self.inputs:
        name = el.name
        if (not name):
            continue
        tag = _nons(el.tag)
        if (tag == 'textarea'):
            results.append((name, el.value))
        elif (tag == 'select'):
            value = el.value
            if el.multiple:
                for v in value:
                    results.append((name, v))
            elif (value is not None):
                results.append((name, el.value))
        else:
            assert (tag == 'input'), ('Unexpected    tag:    %r' % el)
            if (el.checkable and (not el.checked)):
                continue
            if (el.type in ('submit', 'image', 'reset')):
                continue
            value = el.value
            if (value is not None):
                results.append((name, el.value))
    return results
