print STDOUT $foo;
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somewhere? Or are you just printing to "the default filehandle" as in

    print $foo;
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without specifiying it?

If the latter is the case, you'll probably be better of with select and using lexical filehandles.

sub prepare_foo_print {
    my ($foo, $file) = @_;
    open my $fh, '>>', $file or die "bummer: $!\n";
    my $oldfh = select $fh;
    # currently opened $file now is default filehandle
    # (instead of STDOUT)
    print_whatever ($foo);
    select $oldfh;
}
sub print_whatever {
    print shift;
}
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_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}