Check perlreftut; your primary mistakes are:

1. Not sending %list by reference: change(\%list);
2. shift()ing @_ and expecting an aggregate back; instead, use: my $href = shift @_;

Once you have $href, you use %$href wherever you used %A.

foreach (keys %$href) {
  print "$_ = $href->{$_}\n";  # or $$href{$_}
  ...
}
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