> ## Documentation Index
> Fetch the complete documentation index at: https://docs.starknet.io/llms.txt
> Use this file to discover all available pages before exploring further.

# core::starknet::storage::Mutable

A wrapper around different storage related types, indicating that the instance is mutable,
i.e. originally created from a `ref` contract state.

## Signature

```rust theme={null}

#[phantom]
pub struct Mutable {}
```