code: def _init():
      
      import importlib
      import os
      import re
  
      filenames = os.listdir(os.path.dirname(__file__))
  
      module_names = set()
      for filename in filenames:
          match = re.match(r'^(?P<name>[A-Z_a-z]\w*)\.py[co]?$', filename)
          if match:
              module_names.add(match.group('name'))
  
      for module_name in module_names:
          try:
              module = importlib.import_module('.' + module_name, __name__)
          except ImportError:
              continue
  
          for name, member in module.__dict__.items():
              if not isinstance(member, type):
                  # skip non-new-style classes
                  continue
              if not issubclass(member, Engine):
                  # skip non-subclasses of Engine
                  continue
              if member is Engine:
                  # skip "abstract" class Engine
                  continue
  
              try:
                  handle = member.handle
              except AttributeError:
                  continue
  
              engines[handle] = member
docs: Dynamically import engines that initialize successfully.