get_errno
=========
> A way to extract ``errno`` from ``std::io::Error``
## Example
```rust
use std::io::Error;
use get_errno::get_errno;
println!("{}", get_errno(&Error::from_os_error(47)));
// Some(47)
println!("{}", get_errno(&Error::new(ErrorKind::Other, "description", None)));
// None
```
## Status
Experimental
## License
MIT