Groupby Whitelist Cleanup
All of these methods are defined on the base GroupBy class so these essentially are no-ops in current state.

Hello @WillAyd! Thanks for updating the PR.





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

##### Comment last updated on December 25, 2018 at 07:20 Hours UTC can you rebase and ping on green. i think some actual fails. Very much +1 on the goal.  xref #16959 can you merge master # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=h1) Report
> Merging [#23972](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/159772d0c9d49977d4b7f871c62c26e06890143a?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23972/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #23972      +/-   ##
==========================================
+ Coverage    92.3%   92.31%   +<.01%     
==========================================
  Files         163      161       -2     
  Lines       51950    51473     -477     
==========================================
- Hits        47953    47516     -437     
+ Misses       3997     3957      -40
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.7% <100%> (-0.01%)` | :arrow_down: |
| #single | `42.43% <100%> (-0.57%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/groupby/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS9iYXNlLnB5) | `89.79% <100%> (-2.05%)` | :arrow_down: |
| [pandas/core/sparse/scipy\_sparse.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL3NjaXB5X3NwYXJzZS5weQ==) | `97.05% <0%> (-2.95%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `86.09% <0%> (-1.67%)` | :arrow_down: |
| [pandas/io/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2h0bWwucHk=) | `91.2% <0%> (-1.47%)` | :arrow_down: |
| [pandas/core/indexes/timedeltas.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy90aW1lZGVsdGFzLnB5) | `89.18% <0%> (-1.24%)` | :arrow_down: |
| [pandas/io/formats/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvaHRtbC5weQ==) | `97.63% <0%> (-1.01%)` | :arrow_down: |
| [pandas/core/dtypes/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2NvbW1vbi5weQ==) | `94.77% <0%> (-0.86%)` | :arrow_down: |
| [pandas/core/indexes/category.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9jYXRlZ29yeS5weQ==) | `97.87% <0%> (-0.79%)` | :arrow_down: |
| [pandas/compat/numpy/function.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9udW1weS9mdW5jdGlvbi5weQ==) | `87.13% <0%> (-0.78%)` | :arrow_down: |
| ... and [63 more](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23972?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/23972?src=pr&el=footer). Last update [159772d...430d3c1](https://codecov.io/gh/pandas-dev/pandas/pull/23972?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/23972?src=pr&el=h1) Report
> Merging [#23972](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/159772d0c9d49977d4b7f871c62c26e06890143a?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23972/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #23972      +/-   ##
==========================================
+ Coverage    92.3%    92.3%   +<.01%     
==========================================
  Files         163      163              
  Lines       51950    51950              
==========================================
+ Hits        47953    47954       +1     
+ Misses       3997     3996       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.71% <100%> (ø)` | :arrow_up: |
| #single | `42.99% <100%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/groupby/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS9iYXNlLnB5) | `91.83% <100%> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/23972/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `87.84% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23972?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/23972?src=pr&el=footer). Last update [159772d...3f4689f](https://codecov.io/gh/pandas-dev/pandas/pull/23972?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks!