Import top level function from other file

I wonder how does this program work. I haven’t imported adder function in adder.k in main.kt still it works.
I guess both file are part of same package hence it worked.
Any idea?

Both files belong to the default package with no name, so the adder function is available. See more at https://kotlinlang.org/docs/reference/packages.html#packages

Thanks Alexey.
That helps.