What happens if you don't put `1;` at the end of a package? For example, if I remove the `1;` from the following script, the code still runs:

```
#!/usr/bin/perl

package Foo;
print "Begin and Block Demo\n";

BEGIN { 
    print "This is BEGIN Block\n" 
}

END { 
    print "This is END Block\n" 
}

1;

```

Is the `1;` mandatory for package creation? I saw [this question](https://stackoverflow.com/questions/3606528/why-do-you-have-to-put-a-1-at-the-end-of-a-perl-5-module), but it doesn't explain what happens if the `1;` is omitted.