Macro bail 

macro_rules! bail {
    ($err:expr) => { ... };
}

Early return with an error.

Example

use dbrest::bail;
use dbrest::Error;

fn validate(x: i32) -> Result<(), Error> {
    if x < 0 {
        bail!(Error::InvalidQueryParam {
            param: "x".to_string(),
            message: "must be non-negative".to_string(),
        });
    }
    Ok(())
}