def has_settings(*keys)
      keys.each do |key|
        define_method(key) do
          singular_key = key.to_s.singularize.to_sym
          if @settings.key? key
            @settings[key]
          elsif @settings.key? singular_key
            [@settings[singular_key]]
          else
            Squid.configuration.public_send key
          end
        end
      end
    end
def has_settings(*keys)
      keys.each do |key|
        define_method(key) do
          singular_key = key.to_s.singularize.to_sym
          if @settings.key? key
            @settings[key]
          elsif @settings.key? singular_key
            [@settings[singular_key]]
          else
            Squid.configuration.public_send key
          end
        end
      end
    end
For each key, create an attribute reader with a settings value.
 First, check if an option with the key exists.
 For example: {formats: [:currency]} ->> [:currency]
 Then, check is an option with the singular version of the key exists.
 For example: {format: :currency} ->> [:currency]
 Finally, check whether the key has a value in Squid configuration.
 For example: config.formats = [:currency] ->> [:currency]