code: def clean_course(self):
          
          course_id = self.cleaned_data[self.Fields.COURSE].strip()
          if not course_id:
              return None
          try:
              client = EnrollmentApiClient()
              return client.get_course_details(course_id)
          except (HttpClientError, HttpServerError):
              raise ValidationError(ValidationMessages.INVALID_COURSE_ID.format(course_id=course_id))
docs: Verify course ID and retrieve course details.