Transform optional chaining operator (?.) into ES5-compatible code. This Babel plugin allows developers to use the optional chaining syntax in their modern JavaScript code, while ensuring compatibility with older browsers and JavaScript environments that don't natively support this feature. By transforming a?.b into more verbose, but universally understood, code, this plugin enables the use of cleaner, more readable modern syntax across different platforms. It's a crucial tool for developers targeting a wide range of environments.