The only change I would suggest is to change this to if ( false !== strpos( [...] )

It would be highly unlikely that a non-boolean false would be returned here, causing the condition to fail (e.g. the string starting with a comma, being the 0th character) - but it's not outside the realm of possibility.  Beyond that, the [docs](http://php.net/manual/en/function.strpos.php#refsect1-function.strpos-returnvalues) suggest always checking against the boolean value here.