How to use [io.file.copy]

The reference page of io.file.copy has its arguments, constraints and declaration.

Copies the specified file to the specified destination folder and file. Notice, requires the destination folder to exist from before, and the source file to exist from before. This slot will delete any previously existing destination file, before starting the copying process. Just like the save slot, this will evaluate the lambda children before it executes the copying of your file, allowing you to use the results of slots as the destination path for your file.

io.file.copy:/misc/README.md
   .:/misc/backup/README-backup.md

Notice, the folder parts of the destination folder is optional, and if you don’t supply a folder as a part of the path, the source folder will be used by default.