Write a function to search for a regular expression that matches two
or more blank lines in sequence.
Write a function to search for duplicated words, such as `the the'.
See Syntax of Regular Expressions, for information on how to write a regexp (a regular
expression) to match a string that is composed of two identical
halves. You can devise several regexps; some are better than others.
The function I use is described in an appendix, along with several
regexps. See the-the Duplicated Words Function.