text: """`Configuration` provider type specification example."""
  
  import os
  
  from dependency_injector import containers, providers
  
  
  class ApiClient:
      def __init__(self, api_key: str, timeout: int):
          self.api_key = api_key
          self.timeout = timeout
  
  
  class Container(containers.DeclarativeContainer):
  
      config = providers.Configuration()
  
      api_client_factory = providers.Factory(
          ApiClient,
          api_key=config.api.key,
          timeout=config.api.timeout.as_int(),
      )
  
  
  if __name__ == "__main__":
      container = Container()
  
      # Emulate environment variables
      os.environ["API_KEY"] = "secret"
      os.environ["API_TIMEOUT"] = "5"
  
      container.config.api.key.from_env("API_KEY")
      container.config.api.timeout.from_env("API_TIMEOUT")
  
      api_client = container.api_client_factory()
  
      assert api_client.api_key == "secret"
      assert api_client.timeout == 5
  