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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def quote_str(obj):
 r""" Add extra quotes to a string. If the argument is not a string it is returned unmodified. :param obj: Object :type obj: any :rtype: Same as argument For example: 5 '"Hello!"' '\'He said "hello!"\'' """

    if not isinstance(obj, str):
        return obj
    return "'{obj}'".format(obj=obj) if '"' in obj else '"{obj}"'.format(obj=obj)