optional v0.0.12

Copy the badge code for the latest version:

[![licenses](https://licenses.dev/b/cargo/optional)](https://licenses.dev/cargo/optional)

<a href="https://licenses.dev/cargo/optional">
  <img src="https://licenses.dev/b/cargo/optional" alt="licenses" />
</a>

Or the badge code for the 0.0.12 version:

[![licenses](https://licenses.dev/b/cargo/optional/0.0.12)](https://licenses.dev/cargo/optional/0.0.12)

<a href="https://licenses.dev/cargo/optional/0.0.12">
  <img src="https://licenses.dev/b/cargo/optional/0.0.12" alt="licenses" />
</a>