You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/bytewax/src/window/clock
    
    the code of the file until where you have to start completion: use pyo3::exceptions::PyTypeError;
use pyo3::prelude::*;

use crate::errors::tracked_err;
use crate::pyo3_extensions::PyConfigClass;
use crate::pyo3_extensions::TdPyAny;

use self::event_time_clock::EventClockConfig;
use self::system_clock::SystemClockConfig;

use super::Clock;

pub(crate) mod event_time_clock;
pub(crate) mod system_clock;

/// Base
    
    fn downcast(&self, py: Python) -> PyResult<Box<dyn ClockBuilder<TdPyAny>>> {
        if let Ok(conf) = self.extract::<SystemClockConfig>(py) {
            Ok(Box::new(conf))
        } else if let Ok(conf) = self.extract::<EventClockConfig>(py) {
            Ok(Box::new(conf))
        } else {
            let pytype = self.as_ref(py).get_type();
            Err(tracked_err::<PyTypeError>(&format!(
                "Unknown clock_config type: {pytype}"
            )))
        }
    }