# a) make local copy of an array passed directly as parameters
Fred( @orig );
sub Fred {
    # @_ is immediately a local copy of the original
}

# b) ... of an array passed by reference:
Fred( \@orig );
sub Fred {
    my $aref = shift;
    my @copy = @$aref;
    #...
}

# c) ... of a hash passed directly
Fred ( %orig );
sub Fred {
    my %copy = @_;
    #...
}

# d) ... and of a hash passed by reference:
Fred( \%orig );
sub Fred {
    my $href = shift;
    my %copy = %$href;
    #...
}
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