Fix incorrect example in wide_to_long docstring
- [x] closes #25733 
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=h1) Report
> Merging [#25736](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/9eec9b86ddba46075b63aa776f6284188de4f1ce?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25736/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25736   +/-   ##
=======================================
  Coverage   91.25%   91.25%           
=======================================
  Files         172      172           
  Lines       52973    52973           
=======================================
  Hits        48338    48338           
  Misses       4635     4635
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.82% <ø> (ø)` | :arrow_up: |
| #single | `41.74% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/reshape/melt.py](https://codecov.io/gh/pandas-dev/pandas/pull/25736/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS9tZWx0LnB5) | `97.5% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=footer). Last update [9eec9b8...5bda59c](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=h1) Report
> Merging [#25736](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/46639512c06300a9844ea27f90167d5648c9b93a?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25736/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25736   +/-   ##
=======================================
  Coverage   91.26%   91.26%           
=======================================
  Files         173      173           
  Lines       52982    52982           
=======================================
  Hits        48356    48356           
  Misses       4626     4626
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.83% <ø> (ø)` | :arrow_up: |
| #single | `41.75% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/reshape/melt.py](https://codecov.io/gh/pandas-dev/pandas/pull/25736/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS9tZWx0LnB5) | `97.5% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=footer). Last update [4663951...b182905](https://codecov.io/gh/pandas-dev/pandas/pull/25736?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 How does `pytest --doctest-modules pandas/core/reshape/melt.py` look now? Looks like you're close! https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=9462&view=logs&jobId=10b0523a-38de-5c7a-02e7-c2259d583b33&taskId=72638d9d-eff6-5eec-7c2f-7fe1a320272e&lineStart=37&lineEnd=38&colStart=1&colEnd=1

You can hopefully fit all the columns in a line. Closing as stale and superseded by #26010 IIRC this was quite close. Just a whitespace issue. I’d prefer we push it across the line if a maintainer or the original author has time. 

> On Apr 10, 2019, at 00:32, William Ayd <notifications@github.com> wrote:
> 
> Closed #25736.
> 
> —
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