This Error is not strange in the Python world.
The error itself describes what it means.
It means you are actually inconsistent in the use of tabs or spaces for indentation.
HOW TO SOLVE IT.
This error can be solved by choosing one preferred indentation method in your python code.
You can choose to use Tabs or you can use Spaces Only, consistently, all along in your code but not both.
Try doing this, run your code and come back again.