def fetch_nested(key)
      unnest(key).inject(self, :fetch)
    rescue NoMethodError, KeyError
      # return the milliseconds for :now if it is not set explicitly
      return (Time.now.to_f * 1000).to_i if key == :now
      raise MissingVariableError, "the required #{key.inspect} variable is missing."
    end
def fetch_nested(key)
      unnest(key).inject(self, :fetch)
    rescue NoMethodError, KeyError
      # return the milliseconds for :now if it is not set explicitly
      return (Time.now.to_f * 1000).to_i if key == :now
      raise MissingVariableError, "the required #{key.inspect} variable is missing."
    end
allows to fetch values for tag names like 'a.3.c' fetching vars[:a][3][:c]