Function register_custom_function 

pub fn register_custom_function<F>(
    tera: &mut Tera,
    name: &str,
    func: F,
) -> Result<()>
where
    F: Fn(&HashMap<String, Value>) -> Result<Value> + Send + Sync + 'static,

Convenience functions for registering custom functions and filters

Register a custom function with Tera

Arguments

• tera - Tera instance to register with
• name - Function name for template usage
• func - Function implementation