Worked on improving documentation accuracy in the JetBrains/phpstorm-stubs repository, focusing on the PHP Core.php file. Addressed a documentation bug by updating docblocks for the property_exists and trait_exists functions to correctly indicate boolean return types, ensuring they reflect true or false values rather than null. This change enhances the reliability of IDE hints and static analysis, supporting better developer understanding for those relying on the stubs. The work involved careful attention to documentation standards and a strong grasp of PHP language behavior, contributing to more precise code intelligence and improved developer experience within the JetBrains/phpstorm-stubs project.