'Create the <optioninput> element.
Uses **kwargs:
*options*: a list of possible options the user can choose from [REQUIRED]
You must specify at least 2 options.
*correct_option*: the correct choice from the list of options [REQUIRED]'

def create_input_element(self, **kwargs):

    options_list = kwargs.get('options', None)
    correct_option = kwargs.get('correct_option', None)
    assert (options_list and correct_option)
    assert (len(options_list) > 1)
    assert (correct_option in options_list)
    optioninput_element = etree.Element('optioninput')
    options_attr_string = u','.join([u"'{}'".format(o) for o in options_list])
    options_attr_string = u'({})'.format(options_attr_string)
    optioninput_element.set('options', options_attr_string)
    optioninput_element.set('correct', str(correct_option))
    return optioninput_element
