code: function uncommonClasses(node, selectorData) {
  	// eslint no-loop-func:false
  	let retVal = [];
  	let classData = selectorData.classes;
  	let tagData = selectorData.tags;
  
  	if (node.classList) {
  		Array.from(node.classList).forEach(cl => {
  			let ind = escapeSelector(cl);
  			if (classData[ind] < tagData[node.nodeName]) {
  				retVal.push({
  					name: ind,
  					count: classData[ind],
  					species: 'class'
  				});
  			}
  		});
  	}
  	return retVal.sort(countSort);
  }
docs: Given a node and the statistics on class frequency on the page,
  return all its uncommon class data sorted in order of decreasing uniqueness
  @param {Element} node			The node
  @param {Object} classData	The map of classes to counts
  @return {Array}						The sorted array of uncommon class data