def get_or_set_last_reflex_version_check_datetime():
    """Get the last time a check was made for the latest reflex version.
    This is typically useful for cases where the host reflex version is
    less than that on Pypi.

    Returns:
        The last version check datetime.
    """
    reflex_json_file = get_web_dir() / constants.Reflex.JSON
    if not reflex_json_file.exists():
        return None
    # Open and read the file
    data = json.loads(reflex_json_file.read_text())
    last_version_check_datetime = data.get("last_version_check_datetime")
    if not last_version_check_datetime:
        data.update({"last_version_check_datetime": str(datetime.now())})
        path_ops.update_json_file(reflex_json_file, data)
    return last_version_check_datetime
Get the last time a check was made for the latest reflex version.
    This is typically useful for cases where the host reflex version is
    less than that on Pypi.

    Returns:
        The last version check datetime.
    
reflex/utils/prerequisites.py