Macro define_theme

macro_rules! define_theme {
    (NOTHING=) => { ... };
    (
        $(#[$attrs:meta])*
        for = $for_ty:ident ;
        theme_field = $theme_field:ident ;
        $(%[component$($component_attr_control:tt)?])?
        $vis:vis $name:ident $(<$lifetime:lifetime>)? {
            $(
                %[fields$($cows_attr_control:tt)?]
                $(
                    $(#[$field_attrs:meta])*
                    $field_name:ident: $field_ty:ty,
                )*
            )?
    }) => { ... };
    (
        $(#[$attrs:meta])*
        $(%[component$($component_attr_control:tt)?])?
        $vis:vis $name:ident $(<$lifetime:lifetime>)? {
            $(
                %[fields$($cows_attr_control:tt)?]
                $(
                    $(#[$field_attrs:meta])*
                    $field_name:ident: $field_ty:ty,
                )*
            )?
    }) => { ... };
}