re.IGNORECASE
text = 'UPPER PYTHON, lower python, Mixed Python'
re.findall('python', text, flags=re.IGNORECASE)
['PYTHON', 'python', 'Python']
re.sub('python', 'snake', text, flags=re.IGNORECASE)
'UPPER snake, lower snake, Mixed snake'
text = 'UPPER PYTHON, lower python, Mixed Python'
re.findall('python', text, flags=re.IGNORECASE)
['PYTHON', 'python', 'Python']
re.sub('python', 'snake', text, flags=re.IGNORECASE)
'UPPER snake, lower snake, Mixed snake'