2. (2 points) A Haskell variable. A Haskell variable is a sequence of one or more characters which can be either uppercase letter (AZ), lowercase letters (aZ), digits (9), the underscore (_) character, or the apostrophe (') characters. However, the first character must be either a lowercase letters or an underscore character, it cannot be a digit or the apostrophe. For example, both "abc1", "-xyz'" are valid Haskell variables. 4 3. (2 points) US state and zip code in postal addresses. When writing a postal address, the state is usually written as a 2-uppercase-letter abbreviation. There can be an optional space character between the state and the zip code. The zip code is either a simple zip code or a zip +4 code. The simple zip code is simply a group of 5 decimal digits (which can start with the digit 0 ). The zip +4 code is the simple zip code followed by a hyphen () character and then another group of 4 digits. For example, the state and zip code for FSU can be written as either "NC28301", "NC 28301", "NC28301-4252", or "NC 283014252