Add example
Add example to `reorder_levels` function of Pandas DataFrame
Hello @madhuri-15! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:

* In the file [`pandas/core/frame.py`](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py):

> [Line 6818:14](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6818): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6828:14](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6828): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6840:79](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6840): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6848:75](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6848): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6854:14](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6854): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6868:14](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6868): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6877:14](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6877): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6906:84](https://github.com/pandas-dev/pandas/blob/11a0043ea7d3406e9f14b71ae2e0a2454755c70a/pandas/core/frame.py#L6906): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace



##### Comment last updated at 2021-08-15 11:29:15 UTC `reorder_levels` seems to break a lexsort. Can it be documented how to reorder and maintain the lexsorted property, i.e. by calling a `sort` method.

As a follow-on it might be worth proposing an issue to add a `sort` keyword arg to the method so that it can sort if necessary. This looks duplicative of https://github.com/pandas-dev/pandas/pull/42935 , which was opened first - let's close in favour of that one for the time being, we can come back to this if that one goes stale - thanks anyway for your PR, and sorry to do this