If you are referring to my node, there's probably nothing wrong with the documentation, just my quick reading of it. When it says you can use _ in place of $ I got the idea that prototypes (_) and ($) would be the same, which is not the case.

sub foo(_){ warn @_ }
sub goo($){ warn @_ }
foo();
goo();
[download]

output:
Not enough arguments for main::goo at pm3 line 4, near "()"
Execution of pm3 aborted due to compilation errors.