Add the __iter__ method from SelectField so that it is possible to modify the QuerySelectField in a list of checkbox fields.
Add the __iter__ method from SelectField so that it is possible to modify the
QuerySelectField in a list of checkbox fields.

For example:

class DynamicBooleanList(QueryMultipleSelectField):
    widget = widgets.ListWidget(prefix_label=False)
    option_widget = widgets.CheckboxInput()

Khan/wtforms