Improved Documentation

__Changes__:

* Some sentences in the docstrings have been restructured to be more intuitive to users.
* Typos have also been fixed.

__Proposals__:

* We may require to have a documentation guideline that guides how documentation in the module is preferred and be adhered to.
* I recommend the following guide for your consideration: http://docs.python-guide.org/en/latest/writing/documentation/

_If there is more to do, please do suggest._
I think this doc string should clarify the difference between 'TRUNCATE' and 'DELETE'. Would you mind also state the difference here?