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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 unicode_safe (s, encoding=i18n.default_encoding, errors='replace'):
 """Get unicode string without raising encoding errors. Unknown characters of the given encoding will be ignored. @param s: the string to be decoded @type s: any object except None @return: if s is already unicode, return s unchanged; else return decoded unicode string of str(s) @rtype: unicode """

    assert s is not None, "argument to unicode_safe was None"
    if isinstance(s, unicode):
        # s is already unicode, nothing to do
        return s
    return unicode(str(s), encoding, errors)