public function setSignedBody($params)
{
$json = json_encode($params);
$signature = hash_hmac("sha256", $json, Constants::IG_SIGNATURE_KEY);
$this->addParam("signed_body", sprintf("%s.%s", $signature, $json));
$this->addParam("ig_sig_key_version", Constants::IG_SIGNATURE_KEY_VERSION);
}