tabnanny module helps us to check Python source files for
With the help of tabnanny module we can checks Python source files for unclear indentation. If a tabs and spaces are mixed by a file in such a way that throws off indentation, no matter what tab size you're using, the nanny complains and variable.
For example you can see below code.
r1 = 10
r2 = 20
sum = vara + varb
print "vara + varb = %d" % sum
If you will try a correct file with tabnanny.py, then it will not complain as follows
$tabnanny.py -v sum.py
'sum.py': Clean bill of health.