How to avoid HTTP status 429 (too many requests)?

[Rombersoft]

Who can share experiences about problems with HttpStatus 429 (Too many requests)?
I noticed that the developer thought about using the proxy server. Does it exist some statistics about what I must do in order to be banned by Google Corporation? Public API is missing and how much is legal to use google back end in order to show google trends results on my own site???

[nekromoff]

change lines:
141 to: throw new \Exception('Maximum five keywords accepted. Split and loop, if more'); // optional
276 to: throw new \Exception($client->getResponse()->getReasonPhrase().' / '.$client->getResponse()->getStatusCode());

then use sleep($delay) with loop increasing sleep time $delay e.g. by 5s each time, when exception is thrown until you get the trend results.

example:

$result = [];
$sleep = 0;
while ($result == []) {
    try {
        $result = $gt->getInterestOverTime($keyword_group);
    } catch (\Exception $e) {
        $sleep = $sleep + 5;
    }
    sleep($sleep);
}