docstr: Wakeup read*() functions waiting for data or EOF.
code: def _wakeup_waiter(self):
      """Wakeup read*() functions waiting for data or EOF."""
      waiter = self._waiter
      if waiter is not None:
          self._waiter = None
          if not waiter.cancelled():
              waiter.set_result(None)
  
imports: import collections
  import socket
  import sys
  import warnings
  import weakref
  from .None import coroutines
  from .None import events
  from .None import exceptions
  from .None import format_helpers
  from .None import protocols
  from .log import logger
  from .tasks import sleep
label_desc: Use image node_id 5 for calling the StreamReader obj's underlying member method code with example usage: obj._wakeup_waiter() without return types