old_contents: """Context manager base class man-in-the-middling the global stdout."""
  
  import sys
  
  
  class Error(Exception):
    """Base class for all exception of this module."""
  
  
  class InvalidUsageError(Error):
    """Error raised on incorrect API uses."""
  
  
  class StdoutInterceptor():
    """Context manager base class man-in-the-middling the global stdout."""
  
    def __init__(self):
      self._original_stdout = None
  
    def __enter__(self) -> 'StdoutInterceptor':
      """Replaces global stdout and starts printing status after last write."""
      self._original_stdout = sys.stdout
      sys.stdout = self
      return self
  
    def __exit__(self, exc_type, exc_value, traceback) -> None:
      """Terminate this TaskManager and restore global stdout."""
      del exc_type, exc_value, traceback  # Unused.
      if self._original_stdout is None:
        raise InvalidUsageError(
            "Object must be used as a context manager, in a `with:` statement.")
      sys.stdout = self._original_stdout
  
    @property
    def stdout(self):
      """Returns the original stdout this class is replacing."""
      if self._original_stdout is None:
        raise InvalidUsageError(
            "Object must be used as a context manager, in a `with:` statement.")
      return self._original_stdout
  
new_contents: """Context manager base class man-in-the-middling the global stdout."""
  
  import sys
  
  
  class Error(Exception):
    """Base class for all exception of this module."""
  
  
  class InvalidUsageError(Error):
    """Error raised on incorrect API uses."""
  
  
  class StdoutInterceptor():
    """Context manager base class man-in-the-middling the global stdout."""
  
    def __init__(self):
      self._original_stdout = None
  
    def __enter__(self):
      """Replaces global stdout and starts printing status after last write."""
      self._original_stdout = sys.stdout
      sys.stdout = self
      return self
  
    def __exit__(self, exc_type, exc_value, traceback) -> None:
      """Terminate this TaskManager and restore global stdout."""
      del exc_type, exc_value, traceback  # Unused.
      if self._original_stdout is None:
        raise InvalidUsageError(
            "Object must be used as a context manager, in a `with:` statement.")
      sys.stdout = self._original_stdout
  
    @property
    def stdout(self):
      """Returns the original stdout this class is replacing."""
      if self._original_stdout is None:
        raise InvalidUsageError(
            "Object must be used as a context manager, in a `with:` statement.")
      return self._original_stdout
  
subject: Fix invalid annotation. The type of `self` in base class should be left to be deduced to the child type.