macro_rules! define_side_metadata_specs {
(@first_spec $name: ident = (global: $is_global: expr, log_num_of_bits: $log_num_of_bits: expr, log_bytes_in_region: $log_bytes_in_region: expr)) => { ... };
(@prev_spec $last_spec: ident as $last_spec_ident: ident, $name: ident = (global: $is_global: expr, log_num_of_bits: $log_num_of_bits: expr, log_bytes_in_region: $log_bytes_in_region: expr), $($tail:tt)*) => { ... };
(@prev_spec $last_spec: ident as $last_spec_ident: ident,) => { ... };
(last_spec_as $last_spec_ident: ident, $name0: ident = (global: $is_global0: expr, log_num_of_bits: $log_num_of_bits0: expr, log_bytes_in_region: $log_bytes_in_region0: expr), $($tail:tt)*) => { ... };
}