Method concat

crates/vm/src/builtins/list.rs:201–212

(&self, other: &PyObject, vm: &VirtualMachine)

    }

    fn concat(&self, other: &PyObject, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
        let other = other.downcast_ref::<Self>().ok_or_else(|| {
            vm.new_type_error(format!(
                "Cannot add {} and {}",
                Self::class(&vm.ctx).name(),
                other.class().name()
            ))
        })?;
        let mut elements = self.borrow_vec().to_vec();
        elements.extend(other.borrow_vec().iter().cloned());
        Ok(Self::from(elements).into_ref(&vm.ctx))
    }

    fn __add__(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
        self.concat(&other, vm)