DOC: Improved doc string for IntervalIndex + related changes
- [x ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

This PR has Improvements for the doc string for ``IntervalIndex`` + related changes
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=h1) Report
> Merging [#17706](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/074b4850151cd2785f670e1d18c412e46c509f60?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17706/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17706      +/-   ##
==========================================
+ Coverage   91.24%   91.25%   +<.01%     
==========================================
  Files         163      163              
  Lines       49766    49765       -1     
==========================================
  Hits        45411    45411              
+ Misses       4355     4354       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.04% <ø> (+0.01%)` | :arrow_up: |
| #single | `40.34% <ø> (-0.06%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/indexes/interval.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9pbnRlcnZhbC5weQ==) | `92.85% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/sparse/array.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL2FycmF5LnB5) | `91.3% <0%> (-0.29%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.73% <0%> (-0.1%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.44% <0%> (-0.1%)` | :arrow_down: |
| [pandas/io/pytables.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL2lvL3B5dGFibGVzLnB5) | `92.79% <0%> (ø)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.2% <0%> (+1.81%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=footer). Last update [074b485...7dfad50](https://codecov.io/gh/pandas-dev/pandas/pull/17706?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Hello @topper-123! Thanks for updating the PR.



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

##### Comment last updated on September 28, 2017 at 15:55 Hours UTC Ok, all comments taken care of. Hi @jorisvandenbossche . I've found, that the output string from the examples in the ``from_*`` methods is wrong, and I'm guessing they are from an older version of ``IntervalIndex``. The second commit proposal is regarding that.

In addition, the time-based examples for ``pd.interval_range`` don't work. I'l submit a issue regarding that as it must be a code issue. *Edit : filed issue as #17707 on this* > I'm guessing they are from an older version of IntervalIndex

Yes, the repr was changes during the PR process of adding the IntervalIndex, so not examples were updated for that @topper-123 Thanks a lot!