Error when creating a form with PlugIn Sniplets

I have created the following code in a Sniplet, but it foesn’t work, Can you help please.
Regards
Rui
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<?php
function mostrar_formulario()
{
global $PHP_SELF;
?>

<form action=”<?php echo $PHP_SELF; ?>” method=POST>
Nome: <input type=text name=”nome”>
Email: <input type=text name=”email”>

<input type=submit value=”Submeter Dados”>
</form>

<?php
}
?>

<?php
function processa_formulario() {
global $nome;
global $email;
printf(“O Nome %s tem como email %s .”, $_POST[‘nome’], $_POST[’email’]);
}
?>
<?php
if (empty($_POST[‘nome’])) {
mostrar_formulario();
}
else
{
processa_formulario();
}
?>