my $context = $file->open_for_reading( {} );

my $context2 = $file->open_for_reading( { 'path' => $file } );
# OK
my $context_derived
    = $file_derived->open_for_reading( { 'path' => $file, 'join_longcalls' => 1 } );

# this should fail
my $context_derived = $file->open_for_reading( { 'join_longcalls' => 1 } );