class Lookbook::PageCollection

def pages_from_paths(file_paths)
  entities = file_paths.map { |path| PageCollection.entity(path) }
  pages, sections = entities.partition { |page| page.type == :page }
  page_dict = pages.index_by(&:lookup_path)
  sections.each do |section|
    parent = page_dict[section.lookup_path]
    section.parent = parent
    parent.add_section(section)
  end
  pages
end