File system

We want to store the list of trending people in a file on a disk.

Exercise 4.a: write a function with signature fn write_to_disk(path: &str, data: Vec<String>) -> Result<(), io::Error> which writes every string in data on its own line in file located at path.

The method join("\n") applied to a Vec<String> will return a new String with the \n character (line feed) inserted between each line. Do not forget to add an extra '\n' character at the end of the returned string.

To write a string content into a file file_name, you can use std::fs::write(file_name, content) which returns a Result<(), std::io::Error>.

Exercise 4.b: modify your main() function such that you write the trending names into a file named "trending.txt".

You will have to add a new variant to your Error enum in order to encapsulate the std::io::Error if there is a problem when writing a file.

Check that the error detection and reporting works fine by attempting to write in a file you cannot write to (such as "/trending.txt", you most likely don't have the rights to write at the root of your file system).