ecial.
The period <code>.</code> matches any single character,
<code>?</code> means the preceding item is optional,
<code>*</code> means the preceding item may be matched zero or more times,
<code>+</code> means the preceding item must be matched one or more times,
<code>^</code> matches the beginning of a line, and <code>$</code> the end,
<code>\&lt;</code> matches the start of a word, and <code>\&gt;</code> the end,
and <code>\s</code> matches a blank.
It also means that lookahead and lookbehind are not p