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 show_clusters(clusters, sample, covariances, means, figure=None, display=True):
        """!
        @brief Draws clusters and in case of two-dimensional dataset draws their ellipses.
        @details Allocated figure by this method should be closed using `close()` method of this visualizer.