deform problem

I put this into a module:# almost literally taken from# http://deformdemo.repoze.org/pyramid_csrf_demo/import deformimport colander@colander.deferreddef deferred_csrf_default(node, kw):    request = kw.get('request')    csrf_token = request.session.get_csrf_token()    return csrf_token    @colander.deferreddef deferred_csrf_validator(node, kw):    def validate_csrf(node, value):        request = kw.get('request')        csrf_token = request.session.get_csrf_token()        if value != csrf_token: # Where does 'value' come from?!?            raise ValueError('Bad CSRF token')        return validate_csrf    class CSRFSchema(colander.Schema):    csrf = colander.SchemaNode(        colander.String(),        default = deferred_csrf_default,        validator = deferred_csrf_validator,        widget = deform.widget.HiddenWidget(),        )Then I generate a schema:from .csrf import CSRFSchema...def genPlainSchema(schema, fields):    for field in fields:        schema.add(genField(field)) # widgets, etc.    return schemadef genSubSchema(schema, fields, key):    """fields: all fields from the database, key: the current fieldset"""    for field in fields:        if field.fieldset != key:            continue        schema.add(genField(field))    return schema def genSchemaFromFields(fields, fieldsets):    schema = CSRFSchema()    if len(fieldsets) == 0:        result = genPlainSchema(schema, fields)    else:        for fieldset in fieldsets:            label = fieldset.label            if not label:                label = fieldset.name            subschema = colander.SchemaNode(colander.Mapping(), title=label)            schema.add(genSubSchema(subschema, fields, fieldset.id).clone())        result = schema   return result Then the form generation:...    schema = forms.genSchemaFromFields(formfields, groups).bind(request=request)    myform = deform.Form(schema, buttons=('submit',), formid = 'newsletter_create_issue.')and the validation:if 'submit' in request.POST: # needs to be guarded against the formid!    controls = request.POST.items() # at this point, 'controls' contains the correct values    try:        appstruct = myform.validate(controls) # raises an exception, but shouldn't    except:        ...# In