class Sequel::Database

def identifier_output_method
  case @identifier_output_method
  when nil
    @identifier_output_method = @opts.fetch(:identifier_output_method, (@@identifier_output_method.nil? ? identifier_output_method_default : @@identifier_output_method))
    @identifier_output_method == "" ? nil : @identifier_output_method
  when ""
    nil
  else
    @identifier_output_method
  end
end