/// Takes the key for the Rail-fence cipher and returns a corresponding
/// RailFence struct.
///
/// # Panics
/// * If `key` is less than or equal to 0.
Takes the key for the Rail-fence cipher and returns a corresponding
RailFence struct.
Takes the key for the Rail - fence cipher and returns a corresponding RailFence struct .
pub fn new(key: usize) -> Self {
        assert!(key > 0, "`key` must be greater than 0");
        Self { key }
    }
pub fn new ( key : usize ) -> Self { assert ! ( key 0 " " ) ; Self { key } }
Takes the key for the Rail-fence cipher and returns a corresponding
RailFence struct.
Takes the key for the Rail - fence cipher and returns a corresponding RailFence struct .
key
usize
panics
If `key` is less than or equal to 0.
If ` key ` is less than or equal to 0 .