$a[1 (integer)] => 1 (int)<br />
$a[2 (integer)] => 2 (str)<br />
$a[3 (integer)] => 3 (str)<br />
$a[4 (integer)] => 4.1 (float)<br />
$a[5 (integer)] => 5 (str)<br />
$a[5.0 (string)] => 5.0 (str)<br />
$a[5 golden rings (string)] => 5 golden rings (str)<br />
$a[foo (string)] => result of foo() (function)<br />