Function col 

pub fn col<F>(size: u8, f: F) -> Element<Div>
where
    F: FnOnce(Element<Div>) -> Element<Div>,

Create a column with specific size (1-12).

Generates: <div class="col-{size}">...</div>

Example

use ironhtml_bootstrap::grid::col;

let c = col(6, |c| c.text("Half width"));
assert!(c.render().contains(r#"class="col-6"#));