## mark a section (Learn more)

begin = '(?x) (?: ^ # beginning of line | (?<= # or look-behind on: [=>~(?:\[,|&] | (?:\s|;)when\s | (?:\s|;)or\s | (?:\s|;)and\s | (?:\s|;|\.)index\s | (?:\s|;|\.)scan\s | (?:\s|;|\.)sub\s | (?:\s|l|\.)sub!\s | (?:\s|;|\.)gsub\s | (?:\s|;|\.)gsub!\s | (?:\s|;|\.)match\s | (?:\s|;)if\s | (?:\s|;)elsif\s | (?:\s|;)while\s | (?:\s|;)unless\s ) | (?<= # or a look-behind with line anchor: ^when\s # duplication necessary due to limits of regex | ^index\s | ^scan\s | ^sub\s | ^gsub\s | ^sub!\s | ^gsub!\s | ^match\s | ^if\s | ^elsif\s | ^while\s | ^unless\s ) ) \s*((/))(?![*+{}?]) ';

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