MongoDB:将PHP代码转换为Python代码

I was searching a way to combine $in and $regex in mongoDB and found exactly the same question with exactly what I want to do. The problem is that the answer is in PHP and I don't have an idea about it. The question is here.

Do you know if I can find anywhere the same sollution in Python code?

$user_query = preg_replace("/[[:blank:]]+/"," ", $user_query);
$arr_query = explode(' ', $user_query);

if (count($arr_query) > 1) {
    $tmp = array();

    foreach ($arr_query as $q) {
        $tmp[] = new MongoRegex( "/". $q ."/" );
    }

    $who['keywords'] = array('$in' => $tmp);

} else {
    $who['keywords'] = new MongoRegex( "/". $user_query ."/" );
}

$db->collection->find( $who ); 

This is what the code does. Given the string:

"one two three"

It gets converted to the equivalent of :

{ "$in": [
    {"$regex": "one"},
    {"$regex": "two"},
    {"$regex": "three"}
]}

But this regex is exactly the same:

{"$regex": "one|two|three"}

And to get that, then all you need to do is replace the whitespace with a |.