The part that you called "prototyping" before is just the subroutine's forward definition. He gives two things there that get around 'use strict', and the one you used wasn't the one with prototypes.

The very first example in perlsub tells you which one you used:

    To declare subroutines:

    sub NAME;           # A "forward" declaration.
    sub NAME(PROTO);    #  ditto, but with prototypes
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