def to_hash
      hash = {}

      hash['scale'] = "#{scale}x" unless scale.nil?

      (KNOWN_KEYS - [:scale]).each do |key|
        value = self.send(key)
        hash[key.to_s.dasherize] = value.to_s unless value.nil?
      end

      attributes.each do |key, value|
        hash[key.to_s] = value
      end

      hash
    end
def to_hash
      hash = {}

      hash['scale'] = "#{scale}x" unless scale.nil?

      (KNOWN_KEYS - [:scale]).each do |key|
        value = self.send(key)
        hash[key.to_s.dasherize] = value.to_s unless value.nil?
      end

      attributes.each do |key, value|
        hash[key.to_s] = value
      end

      hash
    end
Serialize to hash

 @return [Hash{String => String}]