def scan( glob )
      Dir[ glob ].flat_map { |f| deps( f ) }.uniq.each do |dependency|
        self.require dependency
      end
    end
def scan( glob )
      Dir[ glob ].flat_map { |f| deps( f ) }.uniq.each do |dependency|
        self.require dependency
      end
    end
Parses all of the files in the given glob and adds their
 dependencies to the graph. A file in this glob is not added
 to the graph unless another file in the glob depends on it.