clarify redirection in ops
core.ops involves a _lot_ of redirection.  This decreases some of that redirection (and some redundancy) by implementing functions that show the logic of how some of the args/kwargs are chosen.  The goal is to make it so future debugging can be done without going through `func.im_func.func_closure[1].cell_contents.func_closure...`

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19346?src=pr&el=h1) Report
> Merging [#19346](https://codecov.io/gh/pandas-dev/pandas/pull/19346?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/2952fbd556e1bc4b5fac70c727652b5419e8e096?src=pr&el=desc) will **increase** coverage by `0.01%`.
> The diff coverage is `98.61%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19346/graphs/tree.svg?token=eZ4WkYLtcO&width=650&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/19346?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19346      +/-   ##
==========================================
+ Coverage   91.57%   91.58%   +0.01%     
==========================================
  Files         150      150              
  Lines       48702    48711       +9     
==========================================
+ Hits        44597    44611      +14     
+ Misses       4105     4100       -5
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.95% <98.61%> (+0.01%)` | :arrow_up: |
| #single | `41.76% <98.61%> (+0.04%)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19346?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/ops.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvb3BzLnB5) | `95.29% <100%> (+0.34%)` | :arrow_up: |
| [pandas/core/sparse/array.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL2FycmF5LnB5) | `91.82% <100%> (ø)` | :arrow_up: |
| [pandas/core/sparse/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL3Nlcmllcy5weQ==) | `95.3% <100%> (-0.02%)` | :arrow_down: |
| [pandas/core/panel.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcGFuZWwucHk=) | `96.95% <80%> (+0.12%)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.22% <0%> (-1.74%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `83.83% <0%> (-0.62%)` | :arrow_down: |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `94.6% <0%> (ø)` | :arrow_up: |
| [pandas/core/groupby.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS5weQ==) | `92.15% <0%> (+0.01%)` | :arrow_up: |
| [pandas/core/indexing.py](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhpbmcucHk=) | `93.11% <0%> (+0.49%)` | :arrow_up: |
| ... and [2 more](https://codecov.io/gh/pandas-dev/pandas/pull/19346/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19346?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/19346?src=pr&el=footer). Last update [2952fbd...fe78b73](https://codecov.io/gh/pandas-dev/pandas/pull/19346?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 >  any idea what masker is for, can remove?

It's a fill value used for Series comparisons.  The only place it is used ATM is in _comp_method_SERIES, where it defaults to False and is passed as True for `__ne__`. ping on green. I still have to check that the doc-strings are unchanged from previous though. ping thanks!