text: import os
  import sys
  
  
  def split_key_path(key_path: str):
      sequence = key_path.lower().split('.')
      return sequence[:-1], sequence[-1]
  
  
  # Hack to get the caller's module path.
  def get_caller_path():
      # Frame offset = current frame + loader constructor frame.
      relative_frame_offset = 2
      frame = sys._getframe(relative_frame_offset)
      path = os.path.dirname(os.path.abspath(frame.f_code.co_filename))
      return str(path)
  
  
  # Default cast function, which does nothing.
  def no_cast(x): return x
  
  
  # Special type to distinguish None, explicitly set by user, and not specified default value.
  class NotSet:
      pass
  
  
  NOT_SET = NotSet()
  