Template

New proposals start from this template, located at docs/source/pmep/TEMPLATE.md:

# PMEP NNN: Short title

<!-- Copy to docs/source/pmep/pmep-NNN-short-title.md. The number (next free) is
     assigned once the authorship requirement is met: at least one active core
     contributor among the authors. Until then, keep the NNN placeholder. -->

| | |
|---|---|
| **Status** | Draft |
| **Type** | Standards / Process |
| **Author** | |
| **Created** | YYYY-MM-DD |
| **Supersedes** | none |

## TL;DR

<!-- Mandatory before voting opens. At most 150 words. What changes, in a form
     someone can read in under a minute and vote on. A summary of the decision,
     not of the document. -->

## What it looks like

<!-- Mandatory before voting opens. Code, before and after: the smallest realistic
     example of the change in use. -->

```python
# before
```

```python
# after
```

## Resulting signatures

<!-- Mandatory before voting opens. The public signatures the proposal produces,
     written out: constructors, method signatures, dataclass fields, file-format
     schemas. Only if the proposal defines a file format or on-disk layout:
     write out its structure and give it an initial schema version carried in
     the artifact itself. -->

## Motivation

<!-- The problem, with a concrete instance. Not "this would be cleaner". -->

## Specification

<!-- The normative part. What changes, precisely enough to implement. -->

## Rationale

<!-- Why this design and not the alternatives, including alternatives rejected. -->

## Backwards compatibility

<!-- What breaks, the deprecation path, the version the deprecation lands in, and
     the expected removal version under the project's deprecation window
     (currently five minor releases, and any window still open at 1.0 closes
     there). -->

## Implementation

<!-- A rough list of work items while the proposal is under review. After
     acceptance the items become issues, each linking back here (adding the
     numbers is editorial). All boxes checked moves the status to Final. -->

- [ ]