pls include comments

Matching a Username Description: find the beginning of the string (), followed by any lowercase letter (a-z), number (0-9), an underscore, or a hyphen. Contain f3,16] makes sure that are at least 3 of those characters, but no more than 16. Finally, we want the end of the string ($). Ex: my-us3r_n4m3 String that doesn't match: th1s1s-waytoo 1Ongtobeausername (too long) 2. Matching a Hex Value String that matches: #a3b1 1 3 String that doesn't match: #4d8224 (contains the letter h)