external and internal keywords

You can use external and internal to declare the visibility of your functions and methods.

If you don't declare visibility, Garden will assume that your function or method is only used in the current file.

fun visible_in_the_current_file() {}

If you use external, you are declaring a function that can be used anywhere.

external fun visible_everywhere() {}

internal is reserved for declaring a function that can be used from any file in the current library, but not outside the library.

Implementation note: currently all functions and methods are visible in all files, although garden check will use visibility modifiers to warn on unused functions that aren't declared external.