File.safe_unlink
- deletes the files in arg and returns an array of files deleted

File.syscopy
- copies the file at 1st arg to the file at 2nd arg

Generator#each
- enumerates the elements
- rewinds the generator and only then enumerates the elements

Generator.new
- creates a new generator from an Enumerable object
- creates a new generator from a block

Generator#next?
- returns false for empty generator
- returns true for non-empty generator
- returns true if the generator has not reached the end yet
- returns false if the generator has reached the end
- returns false if end? returns true

Generator#next
- raises an EOFError on empty generator
- raises an EOFError if no elements available
- raises an EOFError if end? returns true
- returns the element at the current position and moves forward
Killed