def point_array(point)
      [point[:path] || raise,
       point[:value] || raise,
       point.fetch(:ts, nil),
       point.fetch(:source, HOSTNAME),
       point[:tags]&.to_wf_tag,
       opts[:tags]&.to_wf_tag]
    end
def point_array(point)
      [point[:path] || raise,
       point[:value] || raise,
       point.fetch(:ts, nil),
       point.fetch(:source, HOSTNAME),
       point[:tags]&.to_wf_tag,
       opts[:tags]&.to_wf_tag]
    end
Make an array which can be used by #hash_to_wf.
 @param point [Hash] a hash describing a point. See #write() for
   the format.
 @raise