What is

use::warnings;
use::strict;
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They don't do anything.

use::warnings;  # Returns the var "*warnings" in the pkg "use".
use::strict;    # Returns the var "*strict"   in the pkg "use".

print $abc;     # "use strict" would give an error (not declared),
                # "use warnings" would give a warning (undefined),
                # but we get nothing.
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You want

use warnings;
use strict;
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