use strict;
use warnings;

sub get_max_index {  

    my (@copyOfArray) = @_;  #make an explicit local copy
    
    my $imax= shift @copyOfArray;  # modifies this copy, but ok
    
    for (@copyOfArray){            # no indices...
        $imax = $_ if $imax < $_;
    }
    return $imax;    
}


my @arr = (1..10);
my $ans = get_max_index(@arr);
print"$ans\n";