enum Root {
    Ty(Arc<String>),
    Str(Arc<String>),
    F64(f64),
    Bool(bool),
    Avatar(Box<(Self, Self)>),
    Tup(Vec<Self>),
    Struct {name: Box<Self>, fields: Vec<Self>},
    Enum {name: Box<Self>, variants: Vec<Self>},
    Instance {class: usize, data: Option<Box<Self>>},
    InstanceTy {ty: Box<Self>, data: Option<Box<Self>>},
}