d.arg('startY', d.T.number),
    ],
  ),
  makeGrid(panels, panelHeight=8, startY=0):
    local sanitizePanels(ps, row) = std.map(
      function(p)
        local sanePanel = panelUtil.sanitizePanel(p);
        (
          if p.type == 'row'
          then sanePanel + {
            panels: sanitizePanels(sanePanel.panels, std.length(sanePanel.panels)),
          }
          else sanePanel + {
            gridPos+: {