new_contents: import struct
  
  
  class ControlRecord:
  
      def __init__(self, version, type_):
          self._version = version
          self._type = type_
  
      @property
      def version(self):
          return self._version
  
      @property
      def type_(self):
          return self._type
  
      def __eq__(self, other):
          if isinstance(other, ControlRecord):
              return other._version == self._version and \
                  other._type == self._type
          return False
  
      @classmethod
      def parse(cls, data: bytes, _schema=struct.Struct(">HH")):
          version, type_ = _schema.unpack_from(data)
          return cls(version, type_)
  
  
  ABORT_MARKER = ControlRecord(0, 0)
  COMMIT_MARKER = ControlRecord(0, 1)
  
subject: Add control_record file