[insert_php]// Check passed arguments
$aOptionalVars = array( ‘amount’, ‘description’, ‘reference’, ‘option’, ‘suboption’, ‘first_name’, ‘last_name’, ‘address’, ‘postal_code’, ‘city’, ‘country’, ‘email’, ‘phone_number’ );

// Prevent PHP notices when we display the form
foreach ( $aOptionalVars as $v ) {
if ( !isset( $_REQUEST[ $v ] ) ) {
// Assign empty values to prevent PHP notices
$_REQUEST[ $v ] = ”;
} else {
// Strip any tags to prevent XSS hacks
$_REQUEST[ $v ] = strip_tags( $_REQUEST[ $v ] );
}
}[/insert_php]