Worked on the ndmitchell/typeshed repository to enhance typing correctness and cross-tool compatibility, focusing on static analysis and type hinting in Python. Addressed a bug by updating the type annotation for the __call__ method of builtins._NotImplementedType from NotImplemented to None, ensuring that instances are not incorrectly treated as callable. This adjustment improved consistency across type checkers such as pyright and reduced false positives, while maintaining awareness of potential impacts on mypy error messaging. The work demonstrated careful attention to the nuances of type systems and contributed to more reliable static analysis workflows within the Python ecosystem over the past month.