How to write a function that accept clourse/function and register that clourse/function to system

[C-Entropy]

With one_shot_systems, I want to organize a CommandRegistry that record commands user can use, and for easy, I write an register_handler function do the register.

#[derive(Resource, Default)]
pub struct CommandRegistry {
    handlers: HashMap<String, SystemId>,
}

impl CommandRegistry {
    pub fn register_handler<I, O, M>(
        &mut self,
        mut commands: Commands,
        name: &str,
        command: impl IntoSystem<I, O, M> + 'static,
    ) where
        I: SystemInput + Send + 'static,
        O: Send + 'static,
    {
        let system_id = commands.register_system(command);
        self.handlers.insert(name.to_string(), system_id.entity());
    }
}

But this functions failed

error[E0308]: mismatched types
    --> src/game/being/command.rs:26:48
     |
16   |     pub fn register_handler<I, O, M>(
     |                             - found this type parameter
...
26   |         self.handlers.insert(name.to_string(), system_id);
     |                       ------                   ^^^^^^^^^ expected `SystemId`, found `SystemId<I, O>`
     |                       |
     |                       arguments to this method are incorrect
     |
     = note: expected struct `bevy::bevy_ecs::system::SystemId<(), ()>`
                found struct `bevy::bevy_ecs::system::SystemId<I, O>`
help: the return type of this call is `bevy::bevy_ecs::system::SystemId<I, O>` due to the type of the argument passed
    --> src/game/being/command.rs:26:9
     |
26   |         self.handlers.insert(name.to_string(), system_id);
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---------^
     |                                                |
     |                                                this argument influences the return type of `insert`
note: method defined here
    --> /home/nil/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/collections/hash/map.rs:1136:12
     |
1136 |     pub fn insert(&mut self, k: K, v: V) -> Option<V> {
     |            ^^^^^^

How can I fix this error?
Great thanks!

[C-Entropy]

Thanks to @hukasu on discord, this works:

pub fn register_handler<M>(
        &mut self,
        mut commands: Commands,
        name: &str,
        command: impl IntoSystem<(), (), M> + 'static,
    )