Macro define_model 

macro_rules! define_model {
    ($(#[$struct_meta:meta])* $name:ident, $enum_name:ident, $update_enum:ident {
        $( $(#[$field_meta:meta])* $field:ident : $ftype:ty $( [ $mode:ident ] )? ),* $(,)?
    }) => { ... };
}