Run-time call by reference deprecated

Run-time call by reference deprecated:
0. function f1(&$form) {...}

1. deprecated version: call the function in a PHP program
...
$form1= ...;
f1(&$form1);


2. revised version
...
$form1= ...;
f1($form1);
//call-by-reference is determined compile-time,
//i.e. determined by the function declaration