Add `__slots__` in classes

[czgdp1807]

Description of the problem

Refer, http://book.pythontips.com/en/latest/__slots__magic.html

Example of the problem

References/Other comments

This is issue is open for anyone to fix.

[udhayacommits]

hello @czgdp1807,
I am trying this one out.
I am a newbie so please bear with me and let me know if something is off.

[czgdp1807]

Hi,

This issue is very easy to fix. You just have to check which class is not having, __slots__ list and add the same to those classes. Note that the list should contain every attribute of the class. Take a look at pydatastructs.linear_data_structures.arrays.DynamicOneDimensionalArray, I have added the __slots__ list there.