<s>[INST] I have a unique requirement for a state machine in Rust. Each state can be associated with a set of named inputs (think of them as events or messages), and when a state receives a particular named input, it updates to a new state, consuming that input. The state machine can also have a set of absorbing states which cause the machine to immediately end when entered.

I can express this requirement as the following data structure:
```rust
use std::collections::HashMap;
use std::hash::Hash;

struct StateMachine<T, U> {
    states: HashMap<T, (U, Option<T>, HashMap<U, T>)>,
    absorbing_states: Vec<T>,
}
```
Here, `T` is the type of the states and `U` is the type of the inputs. The `states` HashMap maps each state to a tuple containing
- the value associated with that state
- the next state to transition to when no input is received
- a HashMap mapping each input to the state it should transition to

The `absorbing_states` is a Vec of states which, when entered, cause the machine to immediately end.

I've been trying to figure out how to implement this state machine but I've been struggling to find the correct way to implement the transition in the context of a generic input type. I want to write a function that can take the current state and an input, and returns the new state and whether the state machine has ended.

Here's a snippet of my attempt:
```rust
fn transition(&self, state: T, input: U) -> (T, bool)?[/INST]