code: def build_dependency_graph(objects)
        DependencyGraph.new.tap do |graph|
          objects.each do |id,object|
            graph[id] = [] # no duplicate IDs
            object.foreign_keys.each do |property|
              value = object[property]
              if value
                graph[id] << value
              end
            end
          end
        end
      end
docs: Builds a dependency graph.
  
   @param [Hash] objects a hash of scraped objects keyed by ID
   @return [DependencyGraph] the dependency graph