DOC: Expose ExcelWriter as part of the Generated API
- [x] closes #21835 
- N/A tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- N/A whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=h1) Report
> Merging [#22359](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/68273a7a8b05049b311ea207f78e6d6f30c6eaf5?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/22359/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #22359   +/-   ##
=======================================
  Coverage   92.05%   92.05%           
=======================================
  Files         169      169           
  Lines       50733    50733           
=======================================
  Hits        46702    46702           
  Misses       4031     4031
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.46% <ø> (ø)` | :arrow_up: |
| #single | `42.24% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/22359/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `96.44% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=continue).
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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=footer). Last update [68273a7...e69316f](https://codecov.io/gh/pandas-dev/pandas/pull/22359?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @WillAyd yeap i'll try to add an example:) > I think we should also prevent the abstract properties and methods from being rendered

Yes, and I would also add a note in the docstring explicitly saying that none of the methods/properties are considered public? (only 'public' usage is what is in the example?) 
To avoid this rendering with sphinx of all methods, you need to do something like this:

```
.. autosummary::
   :toctree: generated/
   :template: autosummary/class_without_autosummary.rst

   ExcelWriter
```

 @newinh this is really shaping up! When I built your latest commit locally I was still seeing the methods and attributes we are trying to hide - were you not seeing these on your end? I think there is still something that needs to be tweaked there.

One other thing that would make this nice - the `mode` argument is getting added in v0.24. If you can expand your example to show how to subsequently append to an Excel file that would cover all the use cases here. > When I built your latest commit locally I was still seeing the methods and attributes we are trying to hide

Looking at how the `Int64Index` docstring is done (there everything is hidden in previous docs: https://pandas.pydata.org/pandas-docs/version/0.22.0/generated/pandas.Int64Index.html (in new docs, you get None listed, but will open a new issue for that, let's follow here the same practice)), I think this needs to be added to the docstring (a bit ugly ...):

```
Attributes
----------
None

Methods
-------
None
``` Can you also add a note in the docstring explicitly saying that none of the methods/properties are considered public? @WillAyd Indeed, I've seen a abstract properties that shouldn't have appeared in docs page. But I thought it is a problem of my local environment. (I first built the document)

Thanks to @jorisvandenbossche, I hid it.

 Added example cases and more details to note.

As you know, there may be some mistakes because of my lack of English. If so, Please let me know:) I do not know why the Travis CI build failed. Where should i look to fix it? Hello @newinh! Thanks for updating the PR.





Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on August 22, 2018 at 09:30 Hours UTC >  slightly prefer the example with append mode but am largely indifferent

@WillAyd what do you mean exactly? > @WillAyd what do you mean exactly?

Your last comment asked to remove a piece that I would slightly prefer to keep in, but not going to lose sleep over it if you think its superfluous and still want to remove 👍  thanks @newinh 