Method truncate

crates/vm/src/stdlib/_io.rs:1683–1698

(
            zelf: PyRef<Self>,
            pos: OptionalOption<PyObjectRef>,
            vm: &VirtualMachine,
        )

        #[pymethod]
        fn truncate(
            zelf: PyRef<Self>,
            pos: OptionalOption<PyObjectRef>,
            vm: &VirtualMachine,
        ) -> PyResult {
            let pos = pos.flatten().to_pyobject(vm);
            let mut data = zelf.lock(vm)?;
            data.check_init(vm)?;
            if !data.writable() {
                return Err(new_unsupported_operation(vm, "truncate".to_owned()));
            }
            data.flush_rewind(vm)?;
            let res = vm.call_method(data.raw.as_ref().unwrap(), "truncate", (pos,))?;
            let _ = data.raw_tell(vm);
            Ok(res)
        }
        #[pymethod]
        fn detach(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult {
            vm.call_method(zelf.as_object(), "flush", ())?;