Check that file exists

# Here
say (Dir.cwd  + %f'input.txt' -> is_file)
say (Dir.cwd  + %d'docs'      -> is_dir)

# Root
say (Dir.root + %f'input.txt' -> is_file)
say (Dir.root + %d'docs'      -> is_dir)

NOTE: To check only for existence, use the method exists