Get value of X-LS-API-Bucket-Level

I am working on adjusting my calls for rate limiting but I can not see the X-LS-API-Bucket-Level value in the response headers (in php) using any of these functions:
var_dump(getallheaders());
var_dump(apache_response_headers());
var_dump(headers_list());
var_dump(get_headers($tokenURL));
curl_getinfo($curl);
var_dump(curl_getinfo($curl,CURLINFO_HEADER_OUT));
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Answers
Anyone????