old_contents: import abc
  import typing as t
  
  
  class FileCollection(metaclass=abc.ABCMeta):
  
      @abc.abstractmethod
      def get_sequences(self) -> t.Dict[str, str]:
          pass
  
      @abc.abstractmethod
      def get_gts(self) -> t.Dict[str, str]:
          pass
  
      @abc.abstractmethod
      def get_subject(self) -> str:
          pass
  
  
  class SubjectFile(FileCollection):
  
      def __init__(self, subject: str, sequence_files: dict=None, gt_files: dict=None) -> None:
          self.subject = subject
          self.sequence_files = sequence_files
          self.gt_files = gt_files
  
      def get_sequences(self) -> t.Dict[str, str]:
          return self.sequence_files
  
      def get_gts(self) -> t.Dict[str, str]:
          return self.gt_files
  
      def get_subject(self) -> str:
          return self.subject
  
new_contents: import abc
  import typing as t
  
  
  class FileCollection(metaclass=abc.ABCMeta):
  
      @abc.abstractmethod
      def get_sequences(self) -> t.Dict[str, str]:
          pass
  
      @abc.abstractmethod
      def get_gts(self) -> t.Dict[str, str]:
          pass
  
      @abc.abstractmethod
      def get_subject(self) -> str:
          pass
  
  
  class SubjectFile(FileCollection):
  
      def __init__(self, subject: str, sequence_files: dict, gt_files: dict=None) -> None:
          self.subject = subject
          self.sequence_files = sequence_files
          self.gt_files = gt_files
  
      def get_sequences(self) -> t.Dict[str, str]:
          return self.sequence_files
  
      def get_gts(self) -> t.Dict[str, str]:
          return self.gt_files
  
      def get_subject(self) -> str:
          return self.subject
  
subject: remove default sequence_files argument for SubjectFile