text: from oscar.core.loading import is_model_registered
  
  from . import abstract_models
  
  __all__ = []
  
  
  if not is_model_registered('payment', 'Transaction'):
      class Transaction(abstract_models.AbstractTransaction):
          pass
  
      __all__.append('Transaction')
  
  
  if not is_model_registered('payment', 'Source'):
      class Source(abstract_models.AbstractSource):
          pass
  
      __all__.append('Source')
  
  
  if not is_model_registered('payment', 'SourceType'):
      class SourceType(abstract_models.AbstractSourceType):
          pass
  
      __all__.append('SourceType')
  
  
  if not is_model_registered('payment', 'Bankcard'):
      class Bankcard(abstract_models.AbstractBankcard):
          pass
  
      __all__.append('Bankcard')
  