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use 5.010; 
my $is_dev_mode = $param->{is_dev_mode} // 1;

my $is_dev_mode = defined $param->{is_dev_mode} ? $param->{is_dev_mode
+} : 1;

#  it would likely help your future self to add a comment here if you 
+do this
my $is_dev_mode = !!$param->{is_dev_mode} || 0;