code: def get_current_tower_context():
      """
      When called inside a TowerContext, returns the TowerContext.
  
      Returns:
          a :class:`BaseTowerContext` instance or None, if not called under a TowerContext.
      """
      return _CurrentTowerContext
  
imports: from abc import ABCMeta, abstractmethod, abstractproperty
  import six
  from ..compat import tfv1
  from ..utils import logger
  from ..utils.argtools import call_only_once
  from ..utils.develop import HIDE_DOC
  from ..utils.naming import MOVING_SUMMARY_OPS_KEY
  from .collection import CollectionGuard
  from .common import get_op_or_tensor_by_name, get_op_tensor_name
label_desc: Use image node_id 1 for calling a global function with example usage: get_current_tower_context() and returns: _CurrentTowerContext