code: function insertCommas(words) {
  	if (words.length < 2) {
  		return words;
  	}
  
  	words = words.slice();
  	const len = words.length;
  	const hasComma = /,$/;
  	let totalCommas = 0;
  
  	if (len > 3 && len <= 6) {
  		totalCommas = rand(0, 1);
  	} else if (len > 6 && len <= 12) {
  		totalCommas = rand(0, 2);
  	} else {
  		totalCommas = rand(1, 4);
  	}
  
  	for (let i = 0, pos, word; i < totalCommas; i++) {
  		pos = rand(0, len - 2);
  		if (!hasComma.test(words[pos])) {
  			words[pos] += ',';
  		}
  	}
  
  	return words;
  }
docs: Insert commas at randomly selected words. This function modifies values
  inside <code>words</code> array
  @param {Array} words