class_docstr: TriggerContext is a utility for handling Trigger invocations. It can be reused by setting the
  key and window fields. No internal state must be kept in the TriggerContext.
class_docstr_tok: ["TriggerContext","is","a","utility","for","handling","Trigger","invocations",".","It","can","be","reused","by","setting","the","key","and","window","fields",".","No","internal","state","must","be","kept","in","the","TriggerContext","."]
code: def __init__(
      self,
      trigger,
      timer_service: LegacyInternalTimerServiceImpl[W],
      state_backend,
  ):
      self._trigger = trigger
      self._timer_service = timer_service
      self._state_backend = state_backend
      self.window = None  # type: W
      self.merged_windows = None
  
imports: from abc import ABC, abstractmethod
  from typing import Generic, TypeVar, List, Iterable
  from pyflink.common.constants import MAX_LONG_VALUE
  from pyflink.datastream.state import StateDescriptor, State, ValueStateDescriptor, ListStateDescriptor, MapStateDescriptor
  from pyflink.datastream.window import TimeWindow, CountWindow
  from pyflink.fn_execution.datastream.process.timerservice_impl import LegacyInternalTimerServiceImpl
  from pyflink.fn_execution.coders import from_type_info, MapCoder, GenericArrayCoder
  from pyflink.fn_execution.internal_state import InternalMergingState
label_desc: Use image node_id 1 to create a new TriggerContext object from inherited base classes: object with example: obj = TriggerContext(trigger, timer_service, state_backend)