code: def get_current_course_run(course, users_active_course_runs):
      
      current_course_run = None
      filtered_course_runs = []
      all_course_runs = course['course_runs']
  
      if users_active_course_runs:
          current_course_run = get_closest_course_run(users_active_course_runs)
      else:
          for course_run in all_course_runs:
              if is_course_run_enrollable(course_run) and is_course_run_upgradeable(course_run):
                  filtered_course_runs.append(course_run)
  
          if not filtered_course_runs:
              # Consider all runs if there were not any enrollable/upgradeable ones.
              filtered_course_runs = all_course_runs
  
          if filtered_course_runs:
              current_course_run = get_closest_course_run(filtered_course_runs)
      return current_course_run
docs: Return the current course run on the following conditions.
  
      - If user has active course runs (already enrolled) then return course run with closest start date
      Otherwise it will check the following logic:
      - Course run is enrollable (see is_course_run_enrollable)
      - Course run has a verified seat and the upgrade deadline has not expired.
      - Course run start date is closer to now than any other enrollable/upgradeable course runs.
      - If no enrollable/upgradeable course runs, return course run with most recent start date.