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 __init__(self, backendsdialog):
        """
        Constructor, just initializes the gtk widgets

        @param backends: a reference to the dialog in which this is
        loaded
        """
        super().__init__()
        self.dialog = backendsdialog
        self.req = backendsdialog.get_requester()
        self._init_liststore()
        self._init_renderers()
        self._init_signals()
        self.refresh()