Macro opg::impl_opg_model

macro_rules! impl_opg_model {
    (generic_simple(nullable): $($type:tt)+) => { ... };
    (generic_simple: $($type:tt)+) => { ... };
    (generic_tuple: ($($type:ident),+)) => { ... };
    (generic_array: $($type:tt)+) => { ... };
    (generic_dictionary: $($type:tt)+) => { ... };
    ($serialized_type:ident: $($type:tt)+) => { ... };
    ($serialized_type:ident(always_inline): $($type:tt)+) => { ... };
}