<h3 id="Package_clause">Package clause</h3>

<p>
A package clause begins each source file and defines the package
to which the file belongs.
</p>

<pre class="ebnf">
PackageClause  = "package" PackageName .
PackageName    = identifier .
</pre>

<p>
The PackageName must not be the <a href="#Blank_identifier">blank identifier</a>.
</p>

<pre>
package math
</pre>

<p>

    * <a href="https://docs.pydantic.dev/latest/usage/types/extra_types/extra_types/" target="_blank"><code>pydantic-extra-types</code></a> - for extra types to be used with Pydantic.
* Now Pydantic Settings is an additional optional package (included in `"fastapi[all]"`). To use settings you should now import `from pydantic_settings import BaseSettings` instead of importing from `pydantic` directly.