def validate_timeout_or_none(option, value):
    """Validates a timeout specified in milliseconds returning
    a value in floating point seconds.
    """
    if value is None:
        return value
    return validate_positive_float(option, value) / 1000.0
Validates a timeout specified in milliseconds returning
    a value in floating point seconds.
    
stackoverflow/venv/lib/python3.6/site-packages/pymongo/common.py