def sanitize_properties(properties):
    """
    Ensures we don't pass any invalid values (e.g. nulls) to hubspot_timestamp

    Args:
        properties (dict):
            the dict of properties to be sanitized

    Returns:
        dict:
            the sanitized dict
    """

    return {
        key: value if value is not None else "" for key, value in properties.items()
    }