>In my opinion the current documentation is correctly formed since the bytearray and str are two different classes in Python they could have different set of functions supported and hence the grouping of functions like islower() to be kept separated for different object types.

This could justify the grouping of the functions themselves, but doesn't explain why the code examples are contained in bytearray instead of str. New users of the language are far more likely to check the docs for the string functions, and thus benefit significantly more from seeing the code examples.