docs: function findCell(cells, c) {
    var lo = 0
      , hi = cells.length-1
      , r  = -1
    while (lo <= hi) {
      var mid = (lo + hi) >> 1
        , s   = compareCells(cells[mid], c)
      if(s <= 0) {
        if(s === 0) {
          r = mid
        }
        lo = mid + 1
      } else if(s > 0) {
        hi = mid - 1
      }
    }
    return r
  }