fixed pep8 warnings
fixed pep8 warnings

dmadeka/bqplot,dmadeka/bqplot,SylvainCorlay/bqplot,SylvainCorlay/bqplot,ChakriCherukuri/bqplot,bloomberg/bqplot,SylvainCorlay/bqplot,ssunkara1/bqplot,ChakriCherukuri/bqplot,ssunkara1/bqplot,ChakriCherukuri/bqplot,bloomberg/bqplot,bloomberg/bqplot