def load_dir(base_dir)
      if File.exist?(dir = File.join(base_dir, 'completions'))
        Dir[dir + '/*.rb'].each {|file| load_file(file) }
        true
      end
    end
def load_dir(base_dir)
      if File.exist?(dir = File.join(base_dir, 'completions'))
        Dir[dir + '/*.rb'].each {|file| load_file(file) }
        true
      end
    end
Loads completion files in given directory.