Replace double quotes with single quotes in string

double2single.py

import re

def replace(obj):
    print(obj.groups())
    if obj.group(0) == '\'':
        return '"'
    if obj.group(0) == '"':
        return '\''
    if obj.group(0) == '"""':
        return '"""'


def main():
    test_string = r'''
"""Doc string"""
list = ["string", "another string"]
string = "blabla"
nested = "Hello 'World'"
escaped = "Some \"escaped\""
    '''
    regex = re.compile(r'''
        (\"\"\")|((?<!\\)\")|(')
    ''', re.VERBOSE
    )
    for line in test_string.split('\n'):
        result = regex.sub(replace, line)
        print(result)

if __name__ == '__main__':
    main()