def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def __normalize_probabilities(self):
        for index_point in range(len(self.__data)):
            probability = 0.0
            for index_cluster in range(len(self.__clusters)):
                probability += self.__rc[index_cluster][index_point]