content: import os
  
  import pytest
  import dash
  from dash._configs import DASH_ENV_VARS
  
  
  @pytest.fixture
  def empty_environ():
      for k in DASH_ENV_VARS.keys():
          if k in os.environ:
              os.environ.pop(k)
  
  
  @pytest.fixture
  def clear_pages_state():
      init_pages_state()
      yield
      init_pages_state()
  
  
  def init_pages_state():
      """Clear all global state that is used by pages feature."""
      dash._pages.PAGE_REGISTRY.clear()
      dash._pages.CONFIG.clear()
      dash._pages.CONFIG.__dict__.clear()
  