Strong typing of functions as parameters in TypeScript: how to declare a type for a callback?

Hello everyone! I recently started learning TypeScript and encountered a problem when passing functions as arguments. In JavaScript, I often did this: ```typescript function processData(data, callback) { const result = data.map(item => item * 2); callback(result); } processData([1, 2, 3], function(result) { console.log(result); }); ``` But in TypeScript, I need to specify types, and I don't understand how to properly declare the type for a function parameter. I tried several options, but they don't work: ```typescript // Option 1: just specify any function processData(data: number[], callback: any) { ... } // Option 2: Function function processData(data: number[], callback: Function) { ... } ``` The first option defeats the whole purpose of TypeScript — type checking is lost.