def directories(directories)
      directories.each do |dir|
        fail "Directory #{dir.inspect} does not exist!" unless Dir.exist?(dir)
      end
      Guard.state.session.watchdirs = directories
    end
def directories(directories)
      directories.each do |dir|
        fail "Directory #{dir.inspect} does not exist!" unless Dir.exist?(dir)
      end
      Guard.state.session.watchdirs = directories
    end
Sets the directories to pass to Listen

 @example watch only given directories
   directories %w(lib specs)

 @param [Array] directories directories for Listen to watch