pylint fixes: consider-merging-isinstance
pylint fixes: consider-merging-isinstance

_stbt/core.py:850:15: [R1701(consider-merging-isinstance), SinkPipeline.draw] Consider merging these isinstance calls to isinstance(obj, (str, unicode))

stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester