text: """
  This namespace represents low-level functionality not intended for daily use,
  but useful for extending Trio's functionality.
  """
  
  import sys
  
  # This is the union of a subset of trio/_core/ and some things from trio/*.py.
  # See comments in trio/__init__.py for details. To make static analysis easier,
  # this lists all possible symbols from trio._core, and then we prune those that
  # aren't available on this system. After that we add some symbols from trio/*.py.
  
  # Generally available symbols
  from ._core import (
      cancel_shielded_checkpoint, Abort, wait_task_rescheduled,
      enable_ki_protection, disable_ki_protection, currently_ki_protected, Task,
      checkpoint, current_task, ParkingLot, UnboundedQueue, RunVar, TrioToken,
      current_trio_token, temporarily_detach_coroutine_object,
      permanently_detach_coroutine_object, reattach_detached_coroutine_object,
      current_statistics, reschedule, remove_instrument, add_instrument,
      current_clock, current_root_task, checkpoint_if_cancelled,
      spawn_system_task, wait_socket_readable, wait_socket_writable,
      notify_socket_close
  )
  
  # Unix-specific symbols
  try:
      from ._core import (
          wait_writable,
          wait_readable,
          notify_fd_close,
      )
  except ImportError:
      pass
  
  # Kqueue-specific symbols
  try:
      from ._core import (
          current_kqueue,
          monitor_kevent,
          wait_kevent,
      )
  except ImportError:
      pass
  
  # Windows symbols
  try:
      from ._core import (
          current_iocp,
          register_with_iocp,
          wait_overlapped,
          monitor_completion_key,
          readinto_overlapped,
          write_overlapped,
      )
  except ImportError:
      pass
  
  from . import _core
  
  # Import bits from trio/*.py
  if sys.platform.startswith("win"):
      from ._wait_for_object import WaitForSingleObject
  