Intellij show provide marker to mark sections(say using comment symbols) inside a class, so as to make sections inside a class collapsible and visible(distinctively).
-each section will be collapsible
-each section can be named
-anything can be put in any of the section(variables, functions etc)
It is for bigger classes with thousands of lines of code so as read them.
It wont be related to coding language, it will just collapse and expand section(which will be defined by user; just the User Interface is given by Intellij)