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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 encode(self, string):
 """Encode a_string as per the canonicalisation encoding rules. See the AWS dev reference page 186 (2009-11-30 version). @return: a_string encoded. """

        if isinstance(string, unicode):
            string = string.encode("utf-8")
        return quote(string, safe="~")