2. Defining Regex from patterns For each of the listed informal pattern descriptions or sets of strings, define a regular ex pression that fits the pattern description or matches all the strings in the set and no other. (a) aac, abc, acc (b) abc, xyz (c) a, ab, abb, abbb, abbbb, . (d) Nonempty strings consisting of lowercase letters in the alphabet (a, b, c, .. ., z) (e) Strings containing substring oe (f) String representing and HTML start or end tag