def time(val, options = {})
      @values[:time] = if val.is_a?(Symbol)
                         TIME_ALIASES[val] || '1' + val.to_s
                       else
                         val
                       end

      build_fill(options[:fill])
      self
    end
def time(val, options = {})
      @values[:time] = if val.is_a?(Symbol)
                         TIME_ALIASES[val] || '1' + val.to_s
                       else
                         val
                       end

      build_fill(options[:fill])
      self
    end
Add group value to relation. To be used instead of `group("time(...)").
 Accepts symbols and strings.

 You can set fill value within options.

    Metrics.time(:hour)
    # select * from metrics group by time(1h)

    Metrics.time("4d", fill: 0)
    # select * from metrics group by time(4d) fill(0)