class ActiveModel::Serializer::Fieldset

def fields
  @fields ||= parsed_fields
end

def fields_for(type)
  fields[type.singularize.to_sym] || fields[type.pluralize.to_sym]
end

def initialize(fields)
  @raw_fields = fields || {}
end

def parsed_fields
  if raw_fields.is_a?(Hash)
    raw_fields.each_with_object({}) { |(k, v), h| h[k.to_sym] = v.map(&:to_sym) }
  else
    {}
  end
end