import re
number = []
p = re.compile(r'((?:Jan|Febr)(?:uary)?|Ma(?:y|r(?:ch)?)|A(?:ug(?:ust)?|pr(?:il)?)|Ju(?:ne?|ly?)|Oct(?:ober)?|(?:Sept|Nov|Dec)(?:ember)?)? *(\d+)')
match = p.search('September 20, 2016')
if match and not match.group(1):
number.append(match.group(2))
else:
number.append("")
print(number)
aW1wb3J0IHJlCm51bWJlciA9IFtdCnAgPSByZS5jb21waWxlKHInKCg/OkphbnxGZWJyKSg/OnVhcnkpP3xNYSg/Onl8cig/OmNoKT8pfEEoPzp1Zyg/OnVzdCk/fHByKD86aWwpPyl8SnUoPzpuZT98bHk/KXxPY3QoPzpvYmVyKT98KD86U2VwdHxOb3Z8RGVjKSg/OmVtYmVyKT8pPyAqKFxkKyknKQptYXRjaCA9IHAuc2VhcmNoKCdTZXB0ZW1iZXIgMjAsIDIwMTYnKQppZiBtYXRjaCBhbmQgbm90IG1hdGNoLmdyb3VwKDEpOgogICAgbnVtYmVyLmFwcGVuZChtYXRjaC5ncm91cCgyKSkKZWxzZToKICAgIG51bWJlci5hcHBlbmQoIiIpCnByaW50KG51bWJlcik=