'Produce a HAR for loading a unit page.'

def record_visit_unit(self, section_title, subsection_title, unit_title):

    course_outline_page = CourseOutlinePage(self.browser, self.course_org, self.course_num, self.course_run).visit()
    course_outline_unit = course_outline_page.section(section_title).subsection(subsection_title).expand_subsection().unit(unit_title)
    har_name = 'UnitPage_{org}_{course}'.format(org=self.course_org, course=self.course_num)
    self.har_capturer.add_page(self.browser, har_name)
    course_outline_unit.go_to()
    self.har_capturer.save_har(self.browser, har_name)
