class DeepPreloader::PolymorphicSpec

def self.parse(data)
  if data.is_a?(Hash)
    specs = data.each_with_object({}) do |(k, v), h|
      h[k.to_s] = DeepPreloader::Spec.parse(v)
    end
    self.new(specs)
  else
    raise ArgumentError.new("Invalid polymorphic spec: '#{data.inspect}' is not a hash")
  end
end