Macro impl_default_config 

macro_rules! impl_default_config {
    ($rule_name:expr, $($field:ident: $value:expr),* $(,)?) => { ... };
    ($rule_name:expr $(,)?) => { ... };
}

Helper macro to implement default_config_section for rules

Usage:

fn default_config_section(&self) -> Option<(String, toml::Value)> {
    impl_default_config!(
        self.name(),
        field1: self.field1,
        field2: self.field2,
    )
}