def normalize_path(path)
      if path.is_a?(String)
        path.split(':')
      elsif path.respond_to?(:each)
        path
      else
        [path]
      end
    end
def normalize_path(path)
      if path.is_a?(String)
        path.split(':')
      elsif path.respond_to?(:each)
        path
      else
        [path]
      end
    end
returns array of strings (directory names in path)