file in Rust

The File struct represents a file that has been opened (it wraps a file descriptor), and gives read and/or write access to the underlying file.
* The open static method can be used to open a file in read-only mode.
* The create static method opens a file in write-only mode. If the file already existed, the old content is destroyed. Otherwise, a new file is created.
* The method lines() returns an iterator over the lines of a file.