Build a nested-case-statements finite automaton that converts all letters in its input to lower case, except within Pascal-style comments and strings. A Pascal comment is delimited by { and }, or by (* and *). Comments do not nest. A Pascal string is delimited by single quotes (' . . . '). A quote character can be placed in a string by doubling it ('Madam, I''m Adam.'). This upper-to-lower mapping can be useful if feeding a program written in standard Pascal (which ignores case) to a compiler that considers upperand lowercase letters to be distinct.