TYP: Make components of Suffixes Optional
The documentation on the parameters that actually are of type `Suffixes`:

> *suffixeslist-like, default is (“_x”, “_y”)*
> A length-2 sequence where each element is optionally a string indicating the suffix to add to overlapping column names in left and right respectively. _**Pass a value of None**_ instead of a string to indicate that the column name from left or right should be left as-is, with no suffix. At least one of the values must not be None.

This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. Yes, still interested in this. @scravy pls merge master and can have a look Do you prefer rebasing or merging from master? either are fine @jreback I rebased.  thanks @scravy 