Macro rustpython_vm::arg_check

macro_rules! arg_check {
    ( $vm: ident, $args:ident ) => { ... };
    ( $vm: ident, $args:ident, required=[$( ($arg_name:ident, $arg_type:expr) ),*] ) => { ... };
    ( $vm: ident, $args:ident, required=[$( ($arg_name:ident, $arg_type:expr) ),*], optional=[$( ($optional_arg_name:ident, $optional_arg_type:expr) ),*] ) => { ... };
}