code: function getBox (items, i, j) {
  	let ilox, iloy, ihix, ihiy, jlox, jloy, jhix, jhiy
  	let iitem = items[i], jitem = items[j]
  
  	if (iitem.length > 2) {
  		ilox = iitem[0]
  		ihix = iitem[2]
  		iloy = iitem[1]
  		ihiy = iitem[3]
  	}
  	else if (iitem.length) {
  		ilox = iloy = iitem[0]
  		ihix = ihiy = iitem[1]
  	}
  	else {
  		ilox = iitem.x
  		iloy = iitem.y
  		ihix = iitem.x + iitem.width
  		ihiy = iitem.y + iitem.height
  	}
  
  	if (jitem.length > 2) {
  		jlox = jitem[0]
  		jhix = jitem[2]
  		jloy = jitem[1]
  		jhiy = jitem[3]
  	}
  	else if (jitem.length) {
  		jlox = jloy = jitem[0]
  		jhix = jhiy = jitem[1]
  	}
  	else {
  		jlox = jitem.x
  		jloy = jitem.y
  		jhix = jitem.x + jitem.width
  		jhiy = jitem.y + jitem.height
  	}
  
  	return [ jlox, iloy, jhix, ihiy ]
  }
docs: return bounding box corresponding to a pass