One of the problems with using regular expressions is that almost any sequence of characters is a valid pattern. This means that it is easy to omit a necessary character and still have a valid regular expression. Omitting a character in a named capturing group is a specific case which can dramatically change the meaning of a regular expression.

Examine the regular expression to find and correct any typos.

In the following example, the regular expression for matcher, r"(P<name>[\w]+)", is missing a "?" and will match only strings of letters that start with "P<name>", instead of matching any sequence of letters and placing the result in a named group. The fixed version, fixed_matcher, includes the "?" and will work as expected.

Python Standard Library: Regular expression operations.

Regular-Expressions.info: Named Capturing Groups.