Method fast_issubclass

crates/vm/src/builtins/type.rs:1256–1258

Determines if `subclass` is actually a subclass of `cls`, this doesn't call __subclasscheck__, so only use this if `cls` is known to have not overridden the base __subclasscheck__ magic method.

(&self, cls: &impl Borrow<PyObject>)

    /// so only use this if `cls` is known to have not overridden the base __subclasscheck__ magic
    /// method.
    pub fn fast_issubclass(&self, cls: &impl Borrow<PyObject>) -> bool {
        self.as_object().is(cls.borrow()) || self.mro.read()[1..].iter().any(|c| c.is(cls.borrow()))
    }

    pub fn mro_map_collect<F, R>(&self, f: F) -> Vec<R>
    where