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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 set_maintainer(self, maintainer):
 # type: (Union[hdx.data.user.User,Dict,str]) -> None """Set the dataset's maintainer. Args: maintainer (Union[User,Dict,str]):
 Either a user id or User metadata from a User object or dictionary. Returns: None """

        if isinstance(maintainer, hdx.data.user.User) or isinstance(maintainer, dict):
            if 'id' not in maintainer:
                maintainer = hdx.data.user.User.read_from_hdx(maintainer['name'], configuration=self.configuration)
            maintainer = maintainer['id']
        elif not isinstance(maintainer, str):
            raise HDXError('Type %s cannot be added as a maintainer!' % type(maintainer).__name__)
        if is_valid_uuid(maintainer) is False:
            raise HDXError('%s is not a valid user id for a maintainer!' % maintainer)
        self.data['maintainer'] = maintainer