[examples] fix pep8 error classes e231 and e241

E231	missing whitespace after ‘,’
E241 (*)	multiple spaces after ‘,’

Note that E241 is not enforced by the pep8 standard as it might reduce readability. Even if it is not enforced I fixed E241 where appropriate.

This is from the pep8 docs
> (*) In the default configuration, the checks E123, E133, E226, E241 and E242 are ignored because they     > are not rules unanimously accepted, and PEP 8 does not enforce them.