docs: function _buildLevel(nodes) {
  		var level = []
  		levels.push(level)
  		var parents = []
  		each(nodes, function(node) {
  			if (!seenPaths[node.path]) {
  				seenPaths[node.path] = true
  				level.push(node.path)
  			}
  			if (node.isRoot) { return }
  
  			node.parent.waitingForNumChildren -= 1
  
  			if (node.parent.waitingForNumChildren == 0) {
  				parents.push(node.parent)
  			}
  		})
  		if (!parents.length) { return }
  		_buildLevel(parents)
  	}