Sub-patterns can be wrapped by parentheses to build a group. This enables to restrict alternations, back reference the group or apply quantifier to
the sub-pattern.
If this group should not be part of the match result or if no reference to this group is required, a non-capturing group can be created by adding
?: behind the opening parenthesis.
However, if this non-capturing group does not have a quantifier, or does not wrap an alternation, then imaging this group is redundant.
Noncompliant code example
r"(?:number)\d{2}"
Compliant solution
r"number\d{2}"
r"(?:number)?\d{2}"
Exceptions
This rule does not report an issue if the non-capturing group is an alternation.
r"(?:number|string)"
