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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 __parse(self, stream):
 """Parse Sorting Hat stream"""


        if not stream:
            raise InvalidFormatError(cause="stream cannot be empty or None")

        json = self.__load_json(stream)

        self.__parse_organizations(json)
        self.__parse_identities(json)
        self.__parse_blacklist(json)