Style fix - use extend instead of for-in-append.
Style fix - use extend instead of for-in-append.

google/openhtf,amyxchen/openhtf,fahhem/openhtf,grybmadsci/openhtf,amyxchen/openhtf,grybmadsci/openhtf,jettisonjoe/openhtf,jettisonjoe/openhtf,fahhem/openhtf,ShaperTools/openhtf,jettisonjoe/openhtf,ShaperTools/openhtf,fahhem/openhtf,google/openhtf,grybmadsci/openhtf,google/openhtf,ShaperTools/openhtf,ShaperTools/openhtf,google/openhtf,jettisonjoe/openhtf,grybmadsci/openhtf,fahhem/openhtf,ShaperTools/openhtf