Libs(PHP): extract helper fn is_postitive_integer

Motivated by superlinter complaining about how long a line was.

Author: svix-onelson

php/src/Webhook.php

@@ -70,8 +70,7 @@ public function verify($payload, $headers)
 
     public function sign($msgId, $timestamp, $payload)
     {
-        $is_positive_integer = is_numeric($timestamp) && !is_float($timestamp + 0) && (int) $timestamp == $timestamp && (int) $timestamp > 0;
-        if (!$is_positive_integer) {
+        if (!self::isPositiveInteger($timestamp)) {
             throw new Exception\WebhookSigningException("Invalid timestamp");
         }
         $toSign = "{$msgId}.{$timestamp}.{$payload}";
@@ -97,4 +96,9 @@ private function verifyTimestamp($timestampHeader)
         }
         return $timestamp;
     }
+
+    private function isPositiveInteger($v)
+    {
+        return is_numeric($v) && !is_float($v + 0) && (int) $v == $v && (int) $v > 0;
+    }
 }