How to call a function inside a PHP script from the command line

I want to know if I can call a function inside a script from the command line, using for example:

$ php script.php minhaFunção() <argumento>

In this case, the function is not inside a class (do I need to be?)

Below my code:

<?php

function dobro($valor) {
    $resultado = $valor + $valor;

    echo $resultado;
}