'Set assignment type for selected cohort.
Arguments:
assignment_type (str): Should be \'random\' or \'manual\''

def set_assignment_type(self, assignment_type):

    css = self._bounded_selector(self.assignment_type_buttons_css)
    self.q(css=css).filter((lambda el: (el.get_attribute('value') == assignment_type))).first.click()
