new_contents: 
  from unittest import TestCase
  from ebu_tt_live.clocks.utc import UTCClock
  from ebu_tt_live.clocks.local import LocalMachineClock
  from ebu_tt_live.clocks.media import MediaClock, SMPTEClock
  from ebu_tt_live.clocks import get_clock
  
  
  class TestInit(TestCase):
  
      def test_get_clock(self):
          clock = get_clock(time_base='clock', clock_mode='local')
          self.assertIsInstance(clock, LocalMachineClock)
          clock = get_clock(time_base='clock', clock_mode='utc')
          self.assertIsInstance(clock, UTCClock)
          clock = get_clock(time_base='media')
          self.assertIsInstance(clock, MediaClock)
          clock = get_clock(time_base='smpte')
          self.assertIsInstance(clock, SMPTEClock)
  
subject: add get_clock tests