In a coding editor like intellij when you write a function eg.
add() {
return a+b;
}
You can collapse this whole function and a + sign will appear on left hand side. so to view the function definition you can expand or collapse it. eg - https://blog.jetbrains.com/idea/2012/03/custom-code-folding-regions-in-intellij-idea-111/
Does notepad++ has such feature or some plugin to do it?