Macro variant_append_value 

macro_rules! variant_append_value {
    ($builder:expr, $value:expr, $object_pat:pat => $object_arm:expr, $list_pat:pat => $list_arm:expr) => { ... };
}

Macro to generate the match statement for each append_variant, try_append_variant, and append_variant_bytes – they each have slightly different handling for object and list handling.