'Retrieves course info page and returns the resume course url
or None if the button doesn\'t exist.'

def get_resume_course_url(self, course_info_url):

    info_page_response = self.client.get(course_info_url)
    content = pq(info_page_response.content)
    return content('.page-header-secondary    .last-accessed-link').attr('href')
